User blog comment:Lancer1289/Are People in Multiplayer Lacking in Intelligence?/@comment-70.143.72.110-20120801165721/@comment-1388547-20120802173238

I think it's just statistics, rather than direct manipulation. There are a *lot* of Gold-level cards. Unless you have everything fully upgraded already, your chances of getting any one specific thing you don't have are low. That said, yes, I'm pretty sure the one of the reasons for random nature of the store system is to get people to spend money on microtransactions.