No, you are right. It is not gambling by definition. It is very similiar emotionally and human response. It is the same in that sense and the same people that would develop an addiction to gambling are at very high risk of wasting a lot of money on these type of features in games.
As far as buying baseball cards go, i can attest to it's potential at being a problem. I spent 90% of my money between the ages of 8 and 14 on baseball cards. It was disposable income at that point and my parents were still taking care of me so it wasn't a true problem. I remember the highs and lows of opening packs and at 14 i realized i could buy the whole year's set for much less money. Collecting baseball cards became lame at that point. I didn't move on to crack though, so it turned out alright.