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 a risky investment where you could earn high or low income but if you have some skills in investing you could probably gain high income. I agree that you must know the sites first before you invest because there are many sites who are just scamming people. Lastly, even it is risky investment you must still invest because investing in bitcoin is one of the best way to gain high income.