They got it covered

I agree to an extent but I'm worried that the owners don't have the greatest intentions with these advertisements. The company that owns RSL owns several casinos. Casinos are heavily regulated in advertising whereas these apps, that tend to prey on the same people who get addicted to gambling, are left unregulated. The small youtuber "Kraut" will be doing a video on the shady dealings within the next few weeks.

Who sponsors him?

Patreon and paypal mostly. I haven't found a video of his that's directly sponsored by a company. He makes videos that aren't the most advertiser friendly as his most popular uploads tend to be about geo-politics and politics in general.