The branch that uBlock sits on is not ad revenue. It's people's annoyance at constantly being subjected to intrusive user tracking, especially for sites that they have little choice to not use. Think social networks and banks. Sure you can refuse to use them entirely on principle, but it's not a practical approach if you want to actually have a life.
On top of that, much of the tracking that does go on is actually blatantly illegal in how it's done, at least in the EU. It's just too small-time to enforce at scale. Doesn't mean I have to take this as a given.
I agree that tracking and ads are different. But uBlock does include ad-blocking functionality. The discussion here suggests that most people use it for that.
> So why do you use any websites that have ads/tracking?
Because it's extremely easy to disable the ads.
> Surely you could avoid them and stick to your high quality paid options?
I don't want to avoid the websites, I want to avoid the ads. If that at some point necessitates avoiding the website then sure, but fortunately it doesn't at the moment.
If uBlock makes itself redundant by killing all ad-supported websites for good, that sounds like a fantastic outcome. In this case, I will personally fund the creator's retirement.