All that being said, there are engineering teams where the leads know all this and do all this. There are more engineering teams where the leads think they are good at this, but really just run all bugs and requests into the product in FIFO mode. The point is that somebody should be in this role of deciding what gets built through a deep understanding of the "why" of the product. A PM who does this job well brings a ton of value. A bad PM kills products and teams.
My advice is to care just as much about the quality of your PM as you do about your boss when making career decisions.
It's clear that "good" PMs bring value. Any "good" INSERT_ROLE_here brings value.
If that means that my project manager gets paid more than I do, but also takes more responsibilities, I'm fine with that.
Good PM if they know the product inside out and they have a good insight on how development works provides a lot of value.
However there are some companies that believes that software engineers are “second class citizens” and roles such as Project Managers and Product Owners just gets paid more without any clear justified contribution.
For me this is a red flag that the company has not realised yet the real value of the software engineers.
A product manager is more like a movie director. She protects the product from feature creep, remains in close contact with users/stakeholders, chooses which bugs to prioritize, etc.
Often there's overlap between the roles but they'll split it up into specialty roles.
Product is closer to user experience. Just like the director knows a script inside out, product knows customer problems inside out. Just like a director knows what happens in script writing and editing, product knows what happens in the requirements and testing/QA stages, but isn't entire responsible for it.
This is different at every organization. I have seen companies that make PMs 100% about profit and market, who then delegate everything else down to others. I've seen ones who work exactly as you describe. And I've seen one where Product manager == Jira monkey.
Based on my experience, while there is a lot of variety, most PMs do worry about the markets and profits as part of their job, even though other teams do the actual sales and marketing. Those concerns are part of understanding the product - who is the market, what are they willing to pay, what monetary value aligns with the solution value. Those answers help drive decisions on roadmap prioritization.
These are just a few of the responsibilities, of course. A good PM is at the center of the business interactions. The interactions between engineering and PM is hardly the entirety of the role. And yes, you will often have to spend time explaining to them how things work so they can be better enabled to have customer discussions and so on. Their job isn't usually about HOW, it's about WHAT/WHY primarily.
My advice: 1. Don't be jealous of the pay. That's down to the market and supply/demand. Jealousy is a cancer that robs you of your happiness and clouds your mind into making career-limiting, and rather juvenile statements like 'The role should really sit with some entry level people'. As Dr. Winston said in How to Speak: "you'll be judged based on the quality of your speaking, the quality of your writing, and the quality of your ideas - in that order."
2. Understand what goes into a software business. I doubt you're explaining 'everything' (and if you are, then maybe you should be a CEO)
3. Think about becoming a PM. The pay is better... :) Really though, the best engineers (e.g. fellows), engineering managers, and senior architects get paid as well or better than PMs. Do what you love and what you're good at, and the pay will follow as your career progresses and you accomplish things of note.