If you're working at a small tech startup, you're likely not making a huge salary. Good, sure, but not huge. It's possible you left your high-paying FAANG job to be developer #3 at a tiny little startup, but in my experience this almost never happens.

Also, $10k is a lot of money. Even if you have it in savings (and I'd agree a lot of tech people technically do), it's a huge gamble on an unknown startup. You're already gambling your time; now you're supposed to also gamble your money?