Also, it seems like eventually you'd run out of money unless you can just retire early, in which case, you have the issue of explaining why you've been out of work for so long and proving you still are up to the task.
The last issue I have is that things I want to enjoy in my leisure time are costly. For example, I'd love to finish my degree and study music, but these things cost money. I want to continue studying piano, but pianos cost money, getting a house costs money, and lessons cost money. I'm sure I would still program and do projects, but it's not the only thing I happen to enjoy. Maybe not everyone has expensive hobbies like I do but I bet a lot of people, for whatever reason, want kids. Those things are expensive!
Also, I take issue with the author assuming that we spend money on luxuries just because we make more. At least for myself, this is not true at all. I've had jobs that were very stressful, and getting things I liked was my means of destressing and justifying staying at my job instead of just becoming a teacher or something (Not that teachers don't have stressful jobs, I just wonder if I'd enjoy it more). I think I'd have trouble keeping some jobs if I couldn't enjoy spending some of what I made.