We shared with the NYAG that these types of boxes in our games are widely used, not just in video games but in the tangible world as well, where generations have grown up opening baseball card packs and blind boxes and bags, and then trading and selling the items they receive.
I'd highly recommend you check out People Make Games' videos on Counter-Strike gambling, which include testimonials from child gambling addicts. And if you still need more convincing, there's also some videos by Coffeezilla.
But I'd also like to see more companies held accountable for this than just Valve.