And there's a lot more to owning "stuff" than anyone generally thinks about. So as I age, I'm actually finding that I want less stuff, but that the reliability of that stuff is important. The "opportunity cost" (paid for by time that you can't get back) can be high enough that it's hard to justify.
So ... things that simply "cost too much". Number one is TV/cable/satellite. It sucks time away faster than you could ever imagine. I haven't completely given it up, but I watch far less than the national average (and usually it's more about spending time with my kids). What else do you have that isn't really worth it? (my boat probably qualifies but I can't give THAT up).
I also see an issue with quality today. So much is designed to be thrown away, but I love to cobble pieces together enough to keep things working. Many devices in my house run on "Frankencords". An old computer power supply is a great source of +5V if you splice the barrel jack from a dead wall-wort to it. One of my favorite past-times is to fix things that other people have decided were junk ... just to say that I can.
I guess this is a long-winded way of warning everyone that you really can't buy happiness ... you have to find it within yourself.