I've more or less followed this advice, and it's worked out for me. For the most part, I used my salary to pay for expenses and stock compensation to build up wealth.
The tricky part is that a lot of this advice is situation-dependent. Should you switch to a riskier company that offers a higher compensation? Sometimes yes, sometimes no. Should you work late to accomplish goals hoping to get a promotion? It depends.
So how are we supposed to know what to do?
The answer, in my opinion, is people. You have to trust people who are trustworthy and avoid people who are not. As an employee, your success depends on the people who hired you--they are the ones who can promote you or cheat you. The best leaders are the ones who realize that helping you advance is going to help them advance. Help your boss accomplish their corporate goals and they will promote you--not as a reward, but as a bet that you will help them on the next goal.
Bad leaders are either too selfish (fail to promote you) or too incompetent (unable to rise, even with your help). You need to learn to avoid them.
Therefore, my advice is this: Look at the leaders in your company--people who could plausibly hire you. Which ones are the best bets? Which ones have both the talent and the integrity to succeed? If you're lucky there's more than one and you can work to get on their team. If you're unlucky, there are none and you need to find a different company.
Problem with this is that this can get you to 1-5 million in net worth (declining fast, someone joining a FANG now certainly won't make it as a single contributor to 5 million, unless they're truly exceptional) (of course 5 million effectively pays you a relatively high level FANG salary just from 4% safe investments ...)
Maybe you can get to 50 million with a reasonable management career.
But let's say you're on this path and you have 3 million or so, at 35/40 years ... then what? Management at all costs? No reasonable job at a FANG will get you to even just double what you have at that point.
Do you sell your stocks immediately and reinvest in SPY?
100% agreed
Warren Buffet also made the point that investing in a company (this applies whether its your capital or your time as an employer) that it was the calibre of the people that determined whether the investment was worthwhile, or not.
And that's why interviews, as a potential employee are so important, you want to know who you will be working for/ with, so you should be asking questions that determine what sort of people you are getting involved with.