Digital Animation is not a lost cause of a degree, OK he probably won't end up working for Pixar, but websites, adverts, etc etc increasingly use it ALL THE TIME.
I would hate to think that my parents sit and make snide comments about my degree, which could be seen as similarly dead-end but wasn't. Instead, they supported me as much as they could. Transport, a listening ear, bought me new things like towels, donated old things like kitchen equipment, and yes financially too (some of which I am paying them back, FWIW). They did the exact same for my brother.
I hope your DS proves you wrong, tbh, as you seem to have a sort of cackling glee at the idea that the world will smack him in the face when he gets out there.
He's worked for two years, paid you £60 a month, and frittered the rest on weed and booze (I presume, was he also running a car/buying his own food etc?) well yes, there will be an adjustment period, he will figure out pretty quickly how to make his money work. There are plenty of bar jobs and that's what I did the whole way through Uni - So that I had spending money as well as living money. I was usually £10 away from totally skint, but I survived. He will too, have a little faith.