I've donated to streamers a few times, though it was more in the $5-20 range. Mostly I did this because I enjoyed the stream, and after watching for more than a few hours, I figure it was only reasonable to pay the streamer for the entertainment I'd received.

I also won't subscribe to any channels (except with the free Twitch Prime sub) because I don't watch any one channel consistently enough to justify it. But if I am watching one channel a lot some month why not donate $5?