A professional will not say they are a professional gambler, but it may show how they say something or words. Also, if you watch from Youtube, I think a "professional" can trick you into providing a well-arranged video to make him look like a professional gambler.
A streamer who wants to make money from YouTube videos will invite people to join but no further explanation from him. And unfortunately, the invitation from the streamer was taken too seriously by the people who watched it, so they finally joined and spent money on gambling.
Come on man, anyone asking people on youtube to join anything means that they are playing you...
Why on earth would you think some random person will take their time to create a video so that random people that person has never met will make money?
Come on man...
on point
usually youtubers have to disclose if they're doing paid promotions and youtube interface includes an option to mark there so they overlay a small sign in the video that says something like "includes paid promotion" but the truth is most of the youtubers don't do it
specially if the activity is a bit more shady or forbidden according to youtube guidelines for publicity.