Though advertising has serious issues, as @MihaiAlisie points out, I think it's also important to remember the good that advertising has done for us. 
Advertising is what has allowed most internet content to be free, which massively improved accessibility; even the poorest people today, in many cases, have access to the same content and info as billionaires and kings.
The reason is that advertising accomplishes near-perfect price discrimination. Viewers are paying with annoyance of watching ads, and creators are paid by advertisers who are in turn paid by viewers who become product buyers; both are roughly proportional to the viewer's income.
That is, if you earn 2x more, annoyance is 2x more costly for you relative to money, and advertisers get 2x more dollars from the possibility that their ads will cause you to buy their products.
With simple payment-for-content, you have to set a price $x, and (usually wealthier) people who can afford it will pay, and those who can't are stuck (or go to thepiratebay.org or sci-hub.tw, but that's another subject...)
Furthermore, payment introduces friction, especially because payment systems are not globally universal; if you don't have a credit card because you're unbanked, you're screwed.
"You can either pay $x and just see the content or otherwise you have to look at ads" seems like an attractive compromise, but is risky due to adverse selection: the people who can afford to pay $x are precisely the demographic that advertisers care most about in the first place.
All of the above is not to deny the very real issues with advertising that people have been pointing out. I just hope that if there is a big social movement against it, we create an alternative that doesn't accidentally destroy the internet's present accessibility in the process.
