It's strictly a hobby for me.
Back in the early 1980s when I was around 18-21ish, I worked for Bill Goepner and Nacho Arredondo at San Diego Sports Collectibles. I had a lot of fun working in their retail store. I did find though, that it soured me on spending large amounts of money on cards. The one example I remember is that at the time, I was looking for a nice 1967 Topps Tom Seaver rookie card. It was a high-demand card at the time and was going for around $80-$100, which wasn't exactly "chump-change" for a college-student/part-time worker. It was also not that easy to find one in San Diego CA.
Anyway, one day I came to work and upon entering the shop, I layed my eyes on a 9-pocket sheet in a display case, with 6 or 7 Seaver rookie cards in it. Suddenly, I just wondered why if it was so expensive, how could I be looking at 6 or more of them at one time (when if I remember correctly, I hadn't even seen ONE of them in a long time...if ever!). I didn't buy any of them, but did get one a bit later.
Edited to add:
I also sold at some local shows in the San Diego/Anaheim area back in the early 1980s. I had thoughts of trying to do it full-time, but after tasting the card shop experience and how it just took a lot of the fun out of collecting (at least for me), I elected to not go in to "the business", and kept it a hobby
Steve