Gamblers love to gamble and if they can't do it with Counter Strike: Global Offensive items, they'll do it with something else instead. In the case of those who lost their favorite platform with CS:GO, they've now moved on to PlayerUnknown's Battlegrounds instead. In the wake of Valve's crackdown on gambling earlier this year, a number of PUBG skin gambling sites have popped up and of course the Youtubers are shilling them like crazy.
The way skin gambling works, is you "bet" a skin you have on the site, effectively transferring it to an escrow account held by the site owners. The site then randomly selects a winner from your pool, transferring your skins and everyone else's to that particular player. Considering some of these skins can have a real monetary value, this is straight up gambling and can see people lose hundreds of dollars worth of skins in minutes if they aren't sure what they're doing.
When you have other sites that let you sell skins for real money, you can start to see the appeal here. People are hoping to win big to cash out big and with many Youtuber's claiming that it's easy to win on such sites, they're doing exactly what some of the biggest culprits were caught out doing in 2016: encouraging their often young audiences to gamble.
You can tell these guys are in on the act, because they have promo codes and free gambling codes. They have free balances, they are sponsored by the sites themselves. It wouldn't be a surprise to learn they had some involvement in the site's management too.
Don't fall for this nonsense and if you have young friends or relatives, make sure they steer well clear of it too.