Well the difference is that most fans don’t mind paying the money to get those items, they don’t typically just hand him money for nothing just because they like him. Twitch subscription is like a concert: you get something in return, but donating large amounts for nothing to already successful streamers is a bit odd.

But not that odd: I’ve backed people on patreon because I liked what they do and wanted to reward them - even though they were already making good money on it - and then never actually accessed the rewards. So I do get it.