"Can't I just stream for 24 hours?"

This is true on all sites. It's well known and often suggested that if you want to grow your audience, stream for at *least* 8 hours consistently. Despite that truth, no site ever devolved to all 24 hour streams. People still chose what works best for them and whats worth it. Streams end up around the same average length and the same will happen here. If not we'll adjust.

"Can I just get my friends to donate to me and / or pay for my own gifted subs?"

You would be losing money on each gift sub, and that additional sub split will probably not make that $ back for you. People who even attempt this, will find that out really quickly. There's also heavy caps on XP for pay -- and XP for dono can be removed at any time if we see it creates any real problem day-to-day.

"Wouldn't it be easy to just have people spam a chat for XP?"

If that's not good content for a user, they won't visit you anymore and you won't end up with that XP you're trying to scam. At the end of the day your viewership is decided by good content. That will level itself out. Additionally chat XP is also capped so you'll only get so far.