YC is not really advocating you to become a worker at a startup. They want you to become a founder. As a founder you don't need to be a huge success for you to be well off. I'm one of 3 founders currently in a bootstrapped company that has done okay. We are approaching end of year 5. This year we will make 700k revenue, 240k profit and 50% yearly growth. Typically this kind of business is not something a VC would consider investing in, but it can still be profitable for the founders.

I'm not very liquid at the moment. My salary is a measly 60k a year. Most of 80k that is my share of the profit will stay in the company instead of go into my pocket, but the 33% ownership in the company is valuable. Very typical valuations for companies in general is 10x profit, which would mean my share of the company is worth 800k. Companies getting strategically acquired can be 20x revenue, which makes my share of the company worth 4.7million.

At FAANG I would have likely made a liquid 300k * 5 = 1.5million, which would allow me to spend more money and enjoy life right now. However, the next 5 years with my company will likely be a lot more valuable. If we manage to grow 30% a year then after 5 years profit will be 900k. That means 300k a year profit share, 3m valuation at 10x profit and 17m valuation at 20x revenue.