Not all startups are the same and saying 'i will never work for a startup again' seems like an overreaction to what happened and a way to just blame everybody, of at least something.

This company sucks, there is no question about it. But what happens after you left it's all on you. Don't blame startups, don't blame the whole world.

You admitted to ignoring red flags, and it sounds like you just went all in without doing the necessary investigation. It's just a lesson for you to either learn, or make a similar mistake very, very soon, and it might happen with a big, established corporation too.

I made a few mistakes in the past by taking a wrong job. Left 3-4 months later. The best experience of my life.