It’s gambling, for 9 year old kids.
With their latest update (3.6), Netmarble has quadrupled down on deciding to turn gaming into a psychological contest of wills, hiding rewards and now characters behind expensive, randomized loot crates. If ever a company failed to learn from the mistakes of others (EA?), it appears to be Netmarble. Worse yet, they then gave away free crystals as a seeming act of generosity, but this too is a casino style plot to get people hooked. The community is up in arms with a boycott. You have been warned...
MNO_OMG about MARVEL Future Fight, v3.6.0