Free money is only to test the site and you won't be able to enjoy much with it because you will probably lose in the crash game. If you really want to play you need to deposit real money. This will have two benefits, first you can enjoy your gambling and secondly you have a good chance of multiply your amount if you play sensibly.
And why can't you multiply the free coins if you play sensibly?
Money is money, deposited or rewarded, and the outcome should be same