"Google pays creators 55% of the ad revenue, so yes Google has to pay for those videos."

Google does not have to pay for videos. If a video brings google enough ad revenue, they willingly give some of it to the channel that made the video. They do not pay a fixed or up-front cost, and assume none of the risk/effort in creating videos. To be fully pedantic, Google doesn't pay for videos in any sense, they pay for the resulting attention.

"People upload to YouTube because YouTube gives them plenty of ad revenue. They don't upload to sites without a lot of ads since that would reduce their ad revenue."

The videos people want to watch are only on Youtube -> Viewers only use Youtube -> Content creators only upload to Youtube -> Repeat... Google's centripetal force prevents competitors from competing.

The videos I watch are an extension of the forum posts and blogs that people have always done not because they are seeking "ad revenue" but simply because passionate people will make stuff about the things they like either for public good or simply because they like doing it.

YouTube was not supposed to be about people trying to make money. That's the old thing. The entire point of YouTube was normal people can upload videos and make channels. The money just attracted the same garbage content as TV had before.