Interestingly the startup I joined had work very similar to the big established company I work for now - cleaning up someone else mess and trying to keep it running.
Ha! No doubt. No shortage of schleps and ‘tech debt’ at startups too. But if the company is doubling every year it will hard to not be swept up by that rising tide in terms of seniority and responsibility.
Reality is starting your own startup is a very risky proposition. Huge upside potential (serious generational wealth), but tons of downside scenarios. If financial security is important to you, then pursuing a more measured approach to reaching some basic level of financial independence is probably a good idea before going that route - I write a lot about this here: https://ramenretirement.com/
On the other hand, starting or joining a startup can be a huge accelerator to career and skills growth. You’ll get opportunities you’d have to wait years for at a larger company. That’s (arguably) the best reason to join someone else’s startup.