I'm willing to bet these are "Sponsor dollars" that RiceGum is using. They already agreed to either give him a certain amount of money for advertising for them, and a certain amount of "prizes" to show "Hey, it really works! See they ship you the items!". I'm willing to bet if he had tried to cash out more they'd have said no.
Same situation with a smaller YouTuber I used to watch, did CSGO cases on a site almost identical to this one with custom cases, custom odds by paying more, etc. The company he got sponsored through got upset with him for cashing out several $1k skins to use as giveaways for his subs, and started the next videos saying he couldn't do that anymore.
Funny part is, he finished the video saying "fuck it" and doing it again anyway, and then he never uploaded another video about that site.