Basically we don't know the risk in every site if you invest money in a site first is you don't know if the site was trusted there are site that can give you small profit but many site are just scamming people who invested.
Investing in bitcoin is also too risky because if do not know how to manage your bitcoin you can't gain more income. In addition to that, there are lot of investment sites and if you want to invest in bitcoin you need to be smart and you need to be patient if you want to gain more income.