Can't help but think that it should be different from just climbing the ranks by buying more cards / investing more ( that's kind of how it feels to me, right now but maybe I'm missing something here ). It would also make things more interesting if there was more going on. It would be less of a long term ( background ) investment. In other words, more interactivity would be cool.
I also understand that those who invest more, deserve more, but it would be nice if there were some more dynamics at play. And, I guess it would help if the game was to be more rewarding for smaller / new users too ( one way or another ).
Just my two SIM ;<)