The whole movie(and a book) was about using this amazing virtual world as the only escape from the shitty horrible reality. It wasn't just entertainment - people go to school there, people have friends there, for many it's the only source of happiness.
And that's what it was for the protagonist, he understands this better than anyone.
But the moment he becomes a billionaire and gets a hot girlfriend, he goes "reality is awesome guys, you should go out more!" While nothing has changed for most people. Fuck you, Wade!
It's like the dumbest cheapest way to add a "moral" to the movie, completely out of character, he'd never do something like this.