Why do I get obsessed with things I don't like

Okay so I bought an iPhone a couple months ago and after that I got obsessed with buying them. I was ALWAYS on Craigslist looking for them, and seeing if I could get them at a good price. I found one so I bought another. Leaving me with 2 of the same phone for no reason!

And now I have a few friends who smoke weed. I got some and now I'm obsessed with it. I hate the smell, and I hate smoking it. I don't use it, just give it away. But I'm constantly thinking about getting more?

It's so weird to me and I don't understand what's going on, I have had depression before but I'm better now. Also I'm 19, female and I think I'm pretty mentally stable.

Added (1). I DO NOT smoke the weed. I don't like it at all. But still obsessed with having it.

Lay off the weed.

You're too materialistic. Try actually smoking that weed once in a while (not every day) and you'll learn that there are better things to do with your time.