It just depends what you are doing on the site and that's by far not unique for CMG.
If you are at a site that pays interest on your balance and you never withdraw because of that, it's basically the same thing in terms of how much you get paid out.

At CMG, if you target upgrading your account, your skills, your cards, etc., then you sure won't make much money, you might find it fun combatting other players with your powerful cards, but that's a different goal.
If you target making money, if you do NOT upgrade anything, if you do NOT use mining boosts to run mining for a few more hours over night at a rate of 5sat an hour, if you SELL absolutely everything you can sell in the market, crystals, cryptocoinz, cards, game tokens, mining boosts and if you trade all the junk coins for btc in the market, you EASILY make 50k coins a month.