That's only massive companies. There aren't that many of them. $500/month from a couple hundred big enterprise clients won't pay the bills.
You need medium sized businesses to pay to use it.
And even massive companies won't pay $500/month when you completely remove the userbase by making it impossible to use without paying. $5/year would remove 99% of the userbase overnight.
Not necessarily?
It's entirely possible to build large and scalable applications from the ground up, and it can even be more efficient to do so. What frameworks do is abstract away a lot of the complexity.
If you genuinely understand what you're doing, frameworks aren't magic. You can implement anything they do yourself. I think it's kind of hard to genuinely understand what you're doing for something at scale without experience with a few different frameworks and how they approach large scale problems, though.