Not generally, but it has happened. And the Brave business model of "block ads, then show our own ads instead" combined with this type of advertising is probably a clearer target than "some guy making uBlock for free".
And what's to stop someone from creating a BATS blocker that simulates attention? Will there be a captcha like challenge?
I don't know about uBlock Origin (which is what you probably meant) but according to press articles AdBlock Plus gets paid money by Google to not block their ads, which feels at least in the ballpark to what Brave is trying to do.
The company behind Adblock plus also has been involved in lawsuits about their product (they won, so far)
Ad-blockers not. But Brave profits by replacing website ads with its own ads.