I'm surprised by how uniformly negative most people's experiences are. The positive stories seem to be the exceptions.
It's like "working" by going to an apprenticeship. Your salary is lower, but you learn a lot.
If you're going to start your own business in the near future, then it might be worth it to work for a startup even if its a huge pay cut all things considered.
If you are working 80 hrs/week churning out code to realize someone else's "vision" who treats you like a slave not a partner, then what are you learning? Apart from not to get suckered again.
You have no idea if you're going to feel like a slave or a partner until you've already taken the job.
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I'd say try it. Don't assume that you will be dissatisfied based on treatment you can't predict.