I don't think its that simple, the tier are clearly not the same just by the fact that every tier has its own benefit. Now i don't think that benefit plays a really big role on picking the tier choices (cause the defining factor is probably income and how likeable the game is for him/her) but if u like the game a lot and decided to donate 30$/month to it then you probably might as well looking for the benefit that came from it to make you feel more special. And i do think patron could be considered as a customer because by just having a patron, dev will be obliged to atleast gives an update every month even without a release anywhere soon, cause if there is no update then people will feel like its a scam.
Probably pretty confusing there but my point is, No, patrons is not just a mere donators, atleast some of them... there are also some people who want to feel special and its also one of a thank you from the dev for supporting the game.