The 24 hours streaming I'd regard as a challenge, as a thing of "Can you make it?", but challenge is not your standard behavior that you do every week. 24 hours also is like doable for an average person with a normal health standard without getting it into total danger.
Streamers, as far as I can see, you have mixed parts of people who do this in their freetime and who it professionally as a kind of entertainer. It's really pretty mixed...
If you're part of the last, well, I'd see it as a thing "I get paid for delivering entertainment, so I've gotta see how I structure my program schedule to not bore my audience".
This includes also such things. Doing long-time plays, for example, or picking up challenges inside the field (like certain difficult games or personal hate-games).
At least that's the way I understand the business.

The hardest I ever read about was, in the point of extreme no-sleep-times, a DJ who managed to mix nonstop for 111 (!) hours. Can't remember anymore who it was, but that was really like a number that was shocking. But you can also be sure, it's only result due to help of drugs (in combination with young age; you recover easier from extreme stuff like this when you're still relatively young).
The DJ managed to survive.
Don't know if that's the official world record for the activity, but it's quite a number that weighs heavy.