I checked some numbers on Facebook: they earn $9 per user per quarter. That's $3 per month per user, with a 80% profit margin. So by these numbers, $1 per month should be more than enough to run social media without ads, but you won't get there without funding it first. And by the time you're big enough to consider getting rid of ads in exchange for charging users, the profit you're making is already much more than the average user will ever be willing to pay.
So Adblock it is