At the end of the day it is always for selfish reasons. Ethots want something; viewers want something. It's all a game of wants. Donating is not out of kindness, it is out of the need for recognition. Sure, they may convince themselves it is out of kindness or whatever, but that is more to justify giving money for (soft/hard-core) porn which is immoral, but donating to show you "care for such a kind person" (during twitch streams or whatever) is different, right...right? This recognition (she knows i exist!!1) they crave is ultimately to one day get to their dream goal which is, by donating enuf, for her to finally privately DM him her physical address so he can come over to fuck her brains out. In short, they want her as a gf/wifu. It's a fantasy thing: "hey maybe im that guy she was waiting for cuz I'M SPECIAL(!). I just have to donate $100". Her acknowledging him ("thank you, xxx") is that partial recognition he was craving (a foot in her door) -- now he is one step closer to his dream goal. Just donate more, hun, ur so close!
And so the grift continues.
As the famous line from the great film, Crimson Tide, said:
"Yeah, horses're fascinating animals. Dumb as fenceposts but very intuitive. In that way they're not too different from high school girls: they may not have a brain in their head, but they do know all the boys want to fuck'em." ~ Capt. Ramsey
But say what you will, she is still a very attractive woman. Case-in-point ...