Having worked at some startups before, there's a difference between folks slowly getting off the boat because "party time is over", and the chaos described by OP.
In the former situation, these people are usually easily replaceable because they weren't committed to start with. I have probably seen over a dozen engineers leaving over the course of a year when more money required better processes and more accountability, and to be frank, nothing really happened.
In the latter though, the high performing, highly committed engineers leave in droves, and create a sort of expertise vacuum that is hard to fill just with new hires.
Telling OP to ignore the writing on the wall and show loyalty to a toxic leader is not good advice.
Is it "normal" for a company to stay "cozy and limitless upside" even as it grows to hundreds of employees?
>If you find yourself relating to this post, please start looking for a new job immediately
The parent post literally mentions quitting as one option.
No it isn't, but that's not relevant to this discussion. Nobody made any claim of limitless upside.
> The parent post literally mentions quitting as one option.
Yes, but it implied you're likely to find the same thing anywhere that's not a super early stage startup, which is not true.