It's one thing to do a paid promotion through a promotor... but to lie and act like it is their own money they are gambling with.. It's not only immorally wrong, it's possibly illegal depending what jurisdiction the streamer is in.
I think these types of marketing tricks should be regulated by law. I have not heard of it being forbidden anywhere. However, it should definitely be regulated at least to make sure that the person who will watch the stream is informed that it is a promotional video and not a real game.