All of the examples I can think of, like radio, YouTube and other video sites, and television, happen to make their money from high quality advertisements: ones that were curated and have higher production values, not random ads from dubious ad networks (except for the YouTube text based ads).

Content paid for with advertising is paid for by advertisers (brands). Quality brands want quality content that will be watched by as many people in their target demographic as possible so they're willing to pay for it.