He doesn't sell his collectibles because he's tired all the time from bad sleep/lack of sleep, he has a full-time jahb, a drinking habit, and an inability to be away from his collectible sweaty near-naked men for very long (those sorts of games generally have some sort of 'stamina' that has to be expended to do anything, slowly replenishes for free over time, and more can always be purchased) and he's the type of person to make everything sound like a Herculean chore. Especially if it's something he's never done before, just taking him out of his comfort zone drains his mental energy at a frightening rate. For him to sell the collectibles, he'd have to research online what each and every piece of plastic crap is worth, list them all, pack them all, and ship them all. He's already decided that it's just too much work for him to handle.
And since Phil doesn't derive personal enjoyment from most of that crap anymore because he doesn't actually like video games anymore, and since he has already decided that it's too difficult to sell them to collect on their value, it has no value to him. And because he's such a narcissist and possible autist with no ability to see things from anyone else's perspective, obviously he can't possibly understand why anyone else would be interested in it either. And since no one cares about, obviously there's no need to include it in his bankruptcy paperwork, right?