the first don't invest in hyip site or ponzi site only wait to scam
you can use youre bitcoin to trade or buy ico coin
another you can invest in bankrool gambling site, bitdouble.io, moneypot or crypto-games.net
I do not think that investing in gambling is a good idea. Now among them there are many scammers. Yes, this sphere is profitable. But it is very difficult to find a reliable project.
You can try, if you are not afraid to lose your coins
Point is to only stick to the sites that have been running for years with a solid reputation. It will not mean that you will walk out with profits, but you'll have far less to worry about, that's for sure. Reward versus risk ratio is relatively okay as on average you'll be making like 5-10% in profits per year (assuming the site's bankroll won't get drained after your investment). I personally don't find it worthwhile. I generate far better returns with just some occasional trading at days with enough volatility. This year alone I already sit above 30%, and we have many months left.