Invest when you find a good site and you trust. Not only invest for invest.
No one can conclude that which is the best site for investment, it will pay you in short term but you cannot expect the same results in long term as they will surely cheat you in future.
If you believe that everyone will cheat you probably should not invest.
Sometimes even the most trusted places run away with the investments of people which always disappoints the users to invest somewhere else next time, some of the sites mostly build a trust among users so that they can take a bigger amount in long run for getting away.
Give a example of site. I see many people claim sites run away with money. But no one gives example.