In my case I even had a decent outcome but you'll always feel like you got screwed because you're off from the founders by an order of magnitude at least.
Better to just angel invest if you have the means or start your own company where you have more upside.
Like any investment, earlier you are, better your returns are. Thats what happens to the founders. It might be that you are better engineer, sales guy than the founders but they were invested into idea of the company earlier that you.
Then engineer #4 at a "hot YC startup" that went from series A to series D in <4 years. my illiquid 18 months of trying to navigate the politics of a hyper-growth company is "worth" significantly more than what I got for 2 years of 9-9/6.
I affected basically zero change there, but by virtue of being early on the rocket, my stock has appreciated massively in value.
I feel more proud of working at the former as I designed and scaled the system from scratch, but would I have been better off doing a hit and run on 2-3 of these "hot" YC companies for a year at a time? Not sure.
The big caveat here is "earlier" means "founder early", not "employee early". By and large, unless you have the same founder-class shares and shareholder rights, you are participating in a lottery just like the founders, except you're even more in the dark than they are, and you are taking on even more downside and less upside than they do. By design.
This might have been tolerable back in say the 80's or 90's when losing a few years of your life to a startup might not have an appreciable effect upon your future lifestyle, and everything was still so new that the experience gained still could cover a noticeable fraction of the entire field's domain knowledge. But I don't advise it for young adults today any longer when even a few years makes a noticeable impact upon a future acquisition timeline of housing/shelter and retirement, with rampant asset inflation under a functional gerontocracy for the foreseeable future. I don't see how the numbers pencil out at this time for employees, even taking the probabilistic distributions into account.
I sure would like to be shown an alternative win-win perspective though, as I think startups are nifty. The startups will be fine though, as there will always be starry-eyed youngsters swarming to startups no matter what, but I wish there were better outcomes with how far the industry has matured and accumulated wealth of all types, than the same dilutive structures we see over and over today. It would accelerate the rate of change.
Just looked on OptionImpact: Senior-most individual contributor (SWE 6) at a post-SeriesA startup indicates a 50th percentile equity grant at 0.28%. If you go all the way up to 90th percentile, you get to 1.1%. Beyond SeriesB+, there are no full-percentage point grants for IC Software Engineers. Managers & Directors have similar equity grants post-SeriesA.
CTO post-SeriesA is 1.5% (50th) and 3.75% (90th). VP Eng is 0.8% (50th) and 2.1% (90th). So even as an exec, whole percentage points aren't a foregone conclusion.
YMMV, but that's the data.