This game, and the previous ones is one of my full time favorite. I've started playing it since v1.3 . The game's too simple and yet to complex in some manner, especially when speaking about mastering it. It was more multiplayer
Have to admit i was that smurfing guy. On higher ranks the game usually squeezes the sweat out of you - to maintain the rank and go higher usually requires tonz of hours of constant practicing without even having a break (because you loose the tense this way). Guys on top mentioned the right reasons for it - low rank friends and that domination feeling. There's a lot of fun in doing that, easy game counts as act of total relaxation without all that perspiration problem.
Didn't made Global though, I was almost close until they released that new rank system tweak patch... 2 victories in a row with a prize of derank = game deleted
About these cases... never got luck with them. Once, bored with the cases, I've sent the rest few available to my friend and he opened asimov awp on the first one...
It's usually better to sell em, there are lot of cheap weapon that are still good looking within a 1-4$. It's of course, if you're not that "fashion" guy who counts the freshest and pricy skins as the best looking.