Since the thread is almost dead, I'm going to necromancy a few hour old topic because I spent a few minutes typing this but also doing so behind a VPN because I am a coward although I am pretty sure at least one person here can guess who I am. Please feel free to not read, but it's probably best for her sake that I have anons pick apart my mental on this if I am being silly.
I mostly donate in the form of gifted subs, usually after a raid. I do send large stream elements donos for special occasions (holidays, birthday, etc.) and I rarely supa anymore outside of the exceedingly rare instance there's a question I want an answer to, that $1 bathroom supa thing people do, and if she does a supa goal (which is almost never.) This is for two reasons (mostly the second.)
The first is the hope of a gift hitting a raider and retaining them for at least a stream when they might have clicked off. This is possibly hoping for too much: I know I have gotten gifted after a raid and still left just because there was another stream I wanted to watch or I just didn't care enough about the talent's content to stick around. Still worth it to me if it does help a little.
The second is the algo thing minimoo mentioned. I am one viewer, I have a limited amount of funds I am able and willing to donate. If donating via YouTube increases her likelihood of being found by more people in the algorithm, then in the long run it could be more valuable than the cut lost by YouTube.
I say could because almost all of the second point is built on a number of assumptions. The first is that Sakana is right at all about YouTube donos boosting the algo. I have not been able to find another other source that speaks to the impact supas/gifted memberships have on a streams visibility to other users, but there is no reason for Sakana to lie about this and it's entirely within reason that Phase Connect would have data that could corroborate this. The second (and most damning) assumption if we assume the first assumption is correct is the impact it has and how exactly it works. For example, does it boost visibility more if 2 two dollar supas are sent because there are more supas being sent, or a $10 supa because more money is being spent. Lastly is if gifted memberships specifically have an impact. To the best of my memory, Sakana only mentioned supas. There's no reason to assume gifted memberships would not have a similar impact, and he never outright said they are not helpful for algo boosting, so I imagine if the first assumption is true than the impact is similar to that of supa chats.
With that all said, if I am wrong then of course that is quite a bit of wasted money to say the least. This does make me feel like I am in a position where I need to keep donating the way I do or else I am more or less admitting I have been wrong this entire time. I know this is the definition of the sunk-cost fallacy, but this is only a problem if I am wrong.