Since he mentioned the Discord benefit for Patreon, I'm guessing the ability to chat with him would be the biggest incentive. The audience really likes getting extra access to a creator and have 2-way communication instead of just being passive viewers.

His other Patreon benefit for the highest tier is early access to videos but in observing other Youtube creators' explanations, it's the live chat that attracts Patreon payments.

I do notice that some Youtubers do the reverse of Patreon tiers from Asianometry. E.g. Real Science: least expensive tiers have early access but no livestream chat; the highest tier has the chat

Everybody's trying to figure out the right mix of incentives for Patreon.