Your story still leaves a lot of room for skepticism. For one, 1.5MM is not actually a very good deal for an engineer in your situation, and likely the company gave you very unfavorable terms. Electing 83b is a fairly irrelevant detail in your story as it only affects taxes, not the outcome of the company.
Your shares are likely going to get hugely diluted exactly because of growth investing like in the article. Investors and founders will essentially trade away your share of the company in new rounds, while they get huge payouts for it, your shares may grow a small amount, again realized over some long time horizon.
Let’s take an extreme example and say your shares double in value (not likely) through the remaining funding rounds, and eventually in another ~7 years you can actually sell them in some liquidity event.
So that’s $3 MM (gross) over 10 years. That works out to be $300,000 / yr in equity compensation.
Certainly very high. But not any kind of crazy number. Definitely there are rank and file engineers in FAANG companies, Wall Street, and other industries getting annual RSUs or bonuses well beyond that without having to wait 10 years to realize it or have the risk that it folds or you get laid off and lose a bunch of future value, and have a high base salary, good benefits, and good work/life balance the whole time.
Given that even a crazy outcome like $3 MM annualized over 10 years isn’t significantly better than other reasonable total comp opportunities, this overall paints a really bad picture for start-ups.
Your case, which is nearly about the best lottery ticket someone could get, is only slightly better than a competitive position at many public companies, finance shops, etc.
Meanwhile, almost all start-up outcomes would be far worse.