I think that (paying relays to prioritize your message) is something to avoid, since it is the source of most problems with spread of misinformation and fake news in centralized social networks.

I havent thought about paying people to repost. But since there is no monetization directly from the network, i don't think this would lead to the closed "cliques" of influencers that repost their own posts in order to increase monetization. Maybe governments could finance something like that to spread misinformation?