They believe that users will agree to be paid to watch some ads in order to earn the BTC to pay to not see ads on their other favorite sites. That is the carrot. The stick is that normal ads will be blocked by default for all users.
Problem is that there are much more lucrative monetization gamification models than advertising, which spam and intrude on users less. Advertising is going to die and be replaced with superior gamification which is more attuned to users' preferences.
Also users and publishers don't want to hand such control over to the Brave team. The only solutions that will be widely adopted will be those not controlled by anyone, i.e. decentralized protocols.
Brenden Eich better stick with his core competency of the programming language Javascript.
Spot on! advertising is the proverbial megaphone, even when it's targeted to people who have shown some 'interest' it's an inferior method compared to even product placement which is subliminal. I know if a blogger has gained my trust for being authentic and knowledgable in something, I will always consider their recommendations, but currently have little way to micro compensate them. Even on this forum there are users who's opinions I rate very highly, and if there was an easy way to tip them I would more often (i.e browser plugin). I'm not going to open a wallet and send them 50 cents, but I would if it literally was one click in my browser.
I don't think anyone ever paid their rent from their TipJar.
If you have a specific project, you can crowdfund to get the necessary economy-of-scale to make it work. But just TipJar that sits there is afaik pretty much insignificant.
So while it sounds nice, the economics ostensibly don't work:
Perhaps you will argue that tips will be greater if people have an easier and more instant way to tip.
Let's say I have 10,000 readers per month at my blog, and 5% of them tip me on average 50 cents. That is $250 per month. That won't even pay rent. And 5% is I think fairly high conversion rate.
Also I think people get tired of tipping. It sounds nice and everyone is motivated at the start, but over time they will grow weary of the cognitive load of, "who do I tip this month?". They have to organize all their web activity and analyze it. The cognitive load is the real killer.