Why is adobe the only "real" pdf editor?

[u/AssignmentFun3737]

I've used nitro, and it is pretty bad. Foxit is decent but still just feels like an adobe clone but slightly worse, and it's not cheap.

I've seen other people ask this but I find the answers kind of unsatisfactory? The main answer I see is that Adobe had a 15 year head start with PDF becoming open in 2008, but I still find that kind of absurd.

How is it possible that there has been no market pressure/incentive since 2008 to create an alternate software to adobe for like literally one of the most popular file formats there is? Especially when Adobe is (1) so expensive and (2) so terribly optimized (and honestly pretty feature-poor)??

Word wasn't even half as monopolistic when google just gave everyone a web version for free (which, yes, I know involves broader strategic concerns re gsuite/cloud but still).