The only way the internet can survive without ads or paywalls is for the person/business hosting the content to pay for everything out of pocket.
A platform like YouTube could never exist without some form of revenue. I understand that there are small platforms out there, such as PeerTube, but they will never be comparable to the scale of YouTube without some form of revenue. Sure, people could grow PeerTube by spinning up their own instances, but then they need to provide their own hardware and storage. At which point you’re spending just as much, or likely more, than you would on a subscription service.