It wasn't a massive mistake if the rapid growth grew their stock enough that paying a few hundred/thousand extra employees for a year or 2 was worth the cost.
it sounds like you knew at the time that it was a mistake to hire this much and you were part of the interview processes.
did you ever speak up, tried to make a case that it is the wrong move?
Pretty similar to the stupid "did you submit a PR?" response to literally any issue with open source software.
Maybe you didn't mean it like that but that's what it sounds like.
You’re not under any obligation and can keep your head down if you like. I can see the spreadsheets with perfect clarity. I need to marry that data with the more complex and hard-to-get view of the elephant that can only from the people who are working with/on it every day.