I don't blame them, but the thing is, they sell their dignity in order to promote gambling, maybe because the offer is too good for them to refuse,
It's all because of money. They're certainly sponsored or paid for doing so. Thus who can't resist if the offer is too good? It's quite normal nowadays. These streamers are attracting their viewers to also gamble on the specific casino. Because this kind of promotion is one of the effective way to lure many people to play.
Seeing someone to win huge is really tempting to try it for yourself. Although it seems these streamers lost their dignity for not even thinking their minor viewers, but that's how it is when it comes to money. They're paid so what can you expect.
Social media or the internet is the biggest means or place or the main focus for most casinos to promote their gambling sites because they can reach more people who will become targets or victims, in any way whether it's with an advertisement or through the intermediary of the stremer with a scenario of doing a video show on one of the social media by showing a big win which makes most people who see it feel tempted. Another thing is that it is clear as you say that it is very unlikely for a stremer to refuse an offer from a casino to help promote their site because of something that the money offered by the casino is usually a very large amount and it is difficult to refuse it because after all everyone needs and wants money.
On the other hand, I am sure and believe that most of the gamblers who now come and get involved in gambling are those who fall or get carried away after seeing the promotional video shows made by the stremers, they do not fully know that the actual video shows that look very tempting are actually nothing more than a temptation that will eventually trap them in many downturns. The fact is that everyone will become blind when they see money, most of them find it difficult to think rationally or consider something first before getting involved if it is about the “ease of getting money” which is actually just a trap. On the other hand, everyone will only think about themselves, including the stringers who cooperate with the casino, they only care about themselves to get a lot of money from the agreement with the casino and they don't think about the fate of the people who see the promotional show and who eventually fall into the following by suffering many problems in it.