I've worked at companies from 30 people to 300 000 people with a brief period at 5 people consulting agencies.

Startups (past 10 people) are good for hungry young programmers. Easy to get into with limited experience. Lots of exposure to lot of stuff. Opportunities to grow experiences quickly and execute at an incredible pace.

Then leave it. It's only leverage to get a better job. One that does provide sane hours, decent pay, healthcare, parental leave, pension...