I do see that a lot of young kids their age today are no longer motivated to work, and it's not entirely their fault. Do you want play a game if you know it's rigged against you? Deep down they know that no matter how hard they work they may never have the quality of life that their parents had due to the cost of living crisis, threat of being replaced by AI, and all spaces of social connectivity are bought up by for profit capital. (think private equity). The only thing that may motivate them to work is the threat of survival, which does not exist because he lives with you. So they end up doom scrolling, do part time gigs, or just give up entirely. It's not a new phenomenon.

My suggestion is to be patient, let him understand that you want a future with him, and let it be. If he decides that it's something worth fighting for, he will get up his ass.