The general truth of things I've found is you wouldn't be the person you are today if you were able to go back and makee any changes with that foresight.
You would be doing it blind as in the butterfly effect, and you could easily go down any number of worse paths or be a much worse person if you think about going down that what if tree scenario. Instead of being regretful of what you think you lost, consider being grateful for what you have.
What you are asking is really a deeper question.
Are you happy with who you are and where you are. If not, what changes do you need to make to get to where you want to be.
You can't go back and change things so you shouldn't be upset about a missed opportunity that you never had. Not letting go of anything that doesn't move you in the direction you want to go is the reason why most people stall and get nowhere.
The only thing you can actually do is take the lessons you've learned, distill them,put the time in to formulate it so you can pass those lessons down, either to your kids, colleagues, or community in some effective form with the intent to give others opportunities you did not have. So they are better prepared than you were. So they have more opportunities than you did.
The next few decades are likely to turn out to be particularly hard, if we manage to survive it at all, and that's being practical not nihilistic.
Financial hardships are borne out of poor financial education and the decisions that arise out of that initial state of education. Not being able to comprehend or understanding how debt works for example is one of the things that we are not taught but critically undermine our success.
Mental health issues often have a physical cause. Either diet, exercise, or it can be circumstances. For example, Toxic Lead/Arsenic/Mercury exposure/poisoning often mimic or induces symptoms similar to ADD/ADHD/Autism and are hard to conclusively test because they bind so quickly. Some people have experienced severe headaches from eating cilantro (because it unbinds those metals if they were previously exposed). This is where finding a doctor that will listen to your concerns and take the appropriate professional steps instead of selling a lie because they get kickback bonuses for meeting budget is necessary.
You should be asking yourself more appropriate questions. For example, why did you waste so much time on WoW, and other games in the past, do you still do it and why?. Did the developers do anything that triggers certain things (sound effects to certain actions), associate things and then repeat/reward in a similar cycle. It wasn't just fun, it was exciting too right? How did they do that?
If you do a bunch of research, you might come to a thought that reframes it like this, and its hard to hear but bear with it and then test whether it could be true based on your experiences.
How do teens generally handle addiction? More specifically, why is it that you couldn't stop eating sugary things on your own when you were a little kid, that your parents had to basically take away the box or limit how many twinkies, donuts, or other sweets physically and how you salivated like you could almost taste it; but now have such a low interest in it now. In most US households this is a globally accepted truth kids can't stop eating sweets until they get amazingly sick from doing it.
You will find over time, that there are deep secrets to be found if you decide to go looking and you can only find them if have your mind open to the possibilities. Secrets that some people can never believe is true. Secrets that you may even be persecuted for knowing, specifically more about how things actually work than others.
Horrifying, amazing, monstrous, and enlightening, the world is ugly and beautiful in different ways.
Getting a degree is a good choice, whether it will pan out as an investment is tough depending on the debt you are going to have (most student debt is bad because it can't be discharged), it probably will situate yourself better than certifications if you can succeed given the only alternative (certifications).
There is a massive amount of fraud in certifications which you don't realize, and you have to recertify regularly. Business Insurance often requires degrees or certifications to prove you are qualified. If you don't have them, its a justification to low-ball your salary and kick you to the curb if you don't come in for pennies. I've had someone in a salary negotiation try to drop my base salary by 20% just because I didn't have a piece of paper (and have a track record of years of professional experience doing the exact same job, years being almost decades). Yes I walked.
The thing no one talks about is how much people lie, mislead, and deceive and then get away with it. Fraud for example is just a deception but what can you do to hold people accountable for it? How do you go about structuring your actions to hold those accountable to what they promised. That's something you should think about as you age.
Any investment you make in yourself is not a lost investment. You never know when you will come across something that is absolute gold, sometimes the authors and books that you hate the most or disagree with the most have something so great that it makes up for hating them (you can still hate them). You can hate them, and use what they taught you for yourself.
That said, there is a lot of junk and snake oil out there.
I would recommend starting with a book like Introduction to NLP because it will give you a solid mental framework to improve everything which compounds and you want your effort towards improvement to compound.
Spaced repetition and the ebbinghaus forgetting curve are useful to know about. Hypnosis is real (not like it is depicted in movies)
Meditation is especially useful (its not what you might expect, its practicing ways to force or still, your thoughts through visualizations and other forms).
Then psychology, Customer Service Rep tactics, sales, all directly impact communication. If you can express yourself clearly, professionally, de-escalate, and handle communications with ease it will command respect and everyone generally will treat you better than someone that can't do those things. If you mispell have bad grammar or poor english there is a widely held bias that you are stupid regardless of any truth to it.
Being able to judge credibility and how lack of credibility works in a negotiation is important as well. When dealing with people that lie, this is critical.
Knowing history is especially important, especially the history they don't dare teach in schools.
Most bad history books simply have a narrative they are trying to push. The best history books provide the context so that you can understand the reasoning of people at that time, the problems they faced, as well as what they would see and hear. In learning to pick these things out, it gives you warning signs because everything is cyclical given a long enough time horizon. If you invest wisely knowing what the trends will be you will hopefully do well. Fraud, Corruption, and Graft these days is everywhere because its gone unchecked and unpunished in important ways since the previous generational cohort took over. You will also be surprised to find that elements of socialism are just about everywhere as well and if you don't understand how to recognize it (and know its failings) you can be side-swiped by trends that depend on that lie.
You need to develop a robust system of personal risk management, and learn to quantify counter-party risk for yourself.
Ideally you need to be debt free with a 20% down payment saved for a starter house by age 30. If your student loans don't allow you to do that; you need to figure out a way for you to make that happen.
If you don't have that taken care of, you likely won't have kids, won't get married, won't be financially secure enough to do anything but work until your dead. Any inheritance you might receive will come too late to be of any useful help. This is what they do not tell you.
Much of what people learned growing up in the late 1970s and forward are at best half-truths, if not outright lies at this point, and those have been repeated since regularly then. It falls far closer to indoctrination than preparation for adulthood.
These are dark times, when you have a chance check out the book 'Influence' by Cialdini. It covers common pitfalls with practical examples of techniques and tactics used by just about everyone of important to manipulate people; its written by a psychologist. Some people would argue that manipulating people is evil but influencing them is not. The difference between the two is whether only one party benefits while the other party losers, or alternatively if both parties receive benefit from it.
If you are a Lord of the Rings fan, you may remember this memorable quote:
https://www.goodreads.com/quotes/12357-i-wish-it-need-not-ha...
Hope this gave you some food for thought. Lots of toxic individuals on social media (mostly bots done at someones behest to persecute others or isolate them). You need a real thick skin to deal with some of those types these days.