Perhaps it is. I'm wondering whether the streamers are playing with their own money, or it's casinos giving thousands to them to play with? I mean, you can play many games, lose in most of them, and make a good video out of the one in which you win big.
I have some theory based on my observation, perhaps right or wrong; I don't know:
At first, streamers usually play with their own money. Maybe they aim to be famous or maybe they just like the game. In this "era," you will see most of them have cheap setup, e.g., basic webcam, headphone, microphone, no chroma key, etc. The revenue is from referrals and Twitch subscription/donation. This era is the most entertaining because the reaction will be epic even if it's not a huge win. Conversely, they will cry if get zeroed
As they gain more and more followers, we will see they start chroma keying with the xxx casino brand. I suspect they got paid similar to the Bitcointalk signature campaign. More followers, more referrals, thus more revenues, and their setup improved dramatically. Since the math is quite simple, as long as the revenue more than the loss from HE, they will get profit from streaming
in the long run.
Assumed weekly bankroll: $5,000 - $1 spin each
Average RTP: 95% -> loss after 5,000 spin = $250
In the long run, as long as they get paid more than $250 per week, they will not get busted. Moreover, judging from how the winning reactions feel "empty" after they got famous. I think they get way more than $250 per week in total (including Twitch subscriptions and referrals).
it's extremely super lucky!
). 
