What I'd learned from almost 15 years running a "startup" hitting multi-million revenue years for the last 6 of the life of the company, is that there is a preternatural bias against you (not personally, but your small company) for business and academic customers. For individuals, I'd imagine its worse.
This bias makes it very hard to achieve escape velocity, never mind low earth orbit. Even when you show multiple million dollar revenues and good margins, investors will demand more before they commit. Customers will demand you jump through more hoops. And will seek to impose fairly crazy T&C on you.
All while you have a team you are trying to care for, a business you are trying to grow.
It f***g sucks. It is as bad for your mental health as STEM graduate school. I'm 5 years out of my business, which was shot in the head behind the barn by our bank.
I am still not fully recovered from that experience.
The comments in this thread about success is really luck in disguise? Yeah, they are spot on. Vanishingly few entrepreneurs really force their way to success. Most are there at the right time and place, with a product that does 80% of what the customer needs. And the customer need is the driving factor.
Note that the same is true of VCs. Who are, as a collection, mostly dumb money. There are a minute fraction who have any real value.
The point of all of this is, no one has your back but you. So take care of yourself. If something isn't working and you feel yourself slipping down a slope, get out. Your health, mental and physical, is simply not worth it.