There's many non-bullshit answers. When you work on your own projects, you rarely can impact many people. It's much easier to leverage the company and their existing user base to make changes that impact more people than you could possibly do so on your own.

Running your own business still has bullshit too. It's just a different type of bullshit. You have to deal with paperwork, accountants, lawyers, marketing, sales, engineering, product, customer support and more. There are probably a few of those at least you'd consider bullshit.

People don't just work for companies because the money is more certain. Sometimes it's nice to be an individual contributor and yes you have a boss or two. It's more of a choose your bullshit adventure.