I've been in streams with less than 100 viewers and seen hundreds of dollars in bits & gifted subs being spent in a single hype train. Are those really unprofitable for Twitch?
Bits are a little more complicated. Donators have to buy bits ahead of time and then donate them. 100 bits is worth $1 to a streamer. But 100 bits will cost between $1.18 and $1.26 depending on how many bits you buy at once. Buying a larger block means paying a little less. (Side note: Once the streamer has received the bits, they can't be taken back, even if the credit card charge that bought the bits is reversed due to a fraud claim)
If a streamer with <100 viewers was getting hundreds of dollars in a single hype train, then either that streamer is very lucky and has a rich viewer that doesn't mind throwing around money, or I'd suspect something fishy is going on. ie, bits being bought with stolen credit cards, or the whole thing is a money laundering scheme.
It would occur regularly to several different streamers I used to watch. Double digit level hype trains were the norm and according to the leaked earnings they were making well over 100K on twitch.
Through even on larger streams most gifts come from a relatively small number of people so there definitely are some outliers like you described but as far as I can tell they are the exception not the norm.
A typical streamer which can life from it but isn't getting rich (or even wealthy!) tends to stream 6+h streams at at least 3 days a week more likely 4-5. Which additional time costs for stuff like filling taxes preparing streams, updating software etc. it's not too rare for streamers to have a 50+ hour week, without getting rich or even wealthy from it. While some pop of and get wealthy or rich it's not the norm. Most do so because they love what they are doing and/or would have problems with other jobs.
I have seen multiple cases of small streamers using Twitch as a form a therapy to help them to overcome social awkwardness or some kinds of anxiety. Also some cases of depressive or otherwise sick people using it to have something like a job even through they are to sick to get any normal job even if they didn't need it for money (to avoid brain rot of being stuck at home and maybe some additional semi-social contacts).
Naturally there are exceptions e.g. of streamers "capturing some whales" and making quite good money with a fraction of the effort of the normal case, but in the end this are exceptions.
