It's not profitable. It's a source of a lot of drama, and ill-will toward the company, it doesn't generate much ad revenue, it's no longer a "feat of engineering" that so many people talked about in the mid-2000s - and it seems like the general populace whom generate a lot of revenue by being targeted on the platform (eg US, North America, Western Europe, Australia) are beginning to shift from adblockers is the exception, to adblockers is the default.
I've worked at F500's where uBlock Origin is part of the Chrome Enterprise profile. Why? It brings security, and performance, to the majority of users. Yes there's occasional issues, but it's worth it.
I suspect we'll see YouTube clients built into AdBlocking software (eg I'm pretty sure SponsorBlock has already begun this). AdBlock and uBlock Origin likely won't implement this, at least initially - but I can definitely see this taking off. At that point, what can Google do?
They'll enforce their walled garden and kill off all Google-ToS breaching extensions.