I disagree kinda with what you're saying here..
Subscriptions on twitch is a way to show support, but depending on the stream, you are in a way a customer. For instance in JPs stream by subbing to the channel you're buying access to the VODs (which means you don't have to wait for them to go live on youtube etc)
you're not "donating" to a stream. it's not a "donation" at all imo. I also do think you're investing in the stream because without people showing their support and "investing" their money to the streamer, the streamer wouldn't be able to produce or make the shows they make. They'd have to find other jobs or stop streaming all together to support themselves and their families.
Donations is what you do when there's a charity involved. Streamers aren't charities. if you're giving money to a streamer through something like PayPal you're "tipping" them.
If you're a patron, usually you're paying $x to "buy" a certain perk at a certain tier, making you a customer.
using terms like "friends" like some streamers do with their audience or "bro's" etc is what's unhealthy. it makes the viewer feel entitled and closer to the streamer then they really are. Some streamers do base their streams off of that model.
People that don't sub, tip, or subscribe via patreon are simply "viewers"
The whole point behind patreon is to support content creators financially so they can give their audience content (product) that they potentially would want, if the content creator had more money. So you're investing $x in hopes that the content creator will eventually be able to produce X content if the patreon reaches its goal.
I think it's naive to not look at it as buying or investing. It's the cold, harsh reality of what streaming/patreon are all about.
rambling over lol.