What can my users do with the ingame currency

I don't know if this is the right place to ask about this type of question, sorry if its not :(

I'm building a site, where you can buy ingame currency with SMS system and bet them on "eSport" matches (professional league/hearthstone/cs:go games).

Where is the problem?
So, people can buy and use the currency. The can win more of if, but it's basically useless, because they can't do noting with it, but bet again. They have no point of giving money and lose them even if they win in the game. I have no idea, how to make this currency useable :/