The list never gets smaller. If anything, it not only gets longer, but the list items themselves grow even more ambitious and far reaching.
I've done great things. I've started sustainable companies, released a prodigious amount of code, and some of it has shifted the course of industry and secured my position in it.
At the same time, I'm exhausted. I'm tired of never taking breaks. My wife feels like she has to beg me to just go for a walk, or do something "non-productive". I view everythig through the lens of productivity, and barely know how to unwind anymore.
There are experiences I'm missing out on. Outdoor activities -- 20s and 30s are the best years for them. Making friends -- it's well known that this gets harder to do as you get older, and many friends you make when younger will be your friends for decades.
If I could give 20 year old me some advice, it would be to pick something off that list of mine, make my work on it economically sustainable, figure out how to get other people working on it, and live a balanced life.
People like us may be able to do the work of 10 engineers, but if you hire 10 engineers, you'll have an economic engine capable of hiring 10 more. If you have the level of energy I do for solving problems, treat sustainability and scale as a problem to be solved; don't try to implement your entire list yourself.