The risk of getting looted to scammed is the biggest one. Most of the time people loosing their money in the scam projects only. Otherwise just look at the market, the bitcoin itself is very stable as compared to other crypto coins or at least it has the potential to recover itself whenever there is worst dump that comes up front. So we can rely on it and there is very much less risk involved as compared to other coins.
The risk is only in terms of altcoins. With ever changing crypto related regulations it is now getting hard for investors to believe in some projects which do not follow them and may get ceased, shut down and much more. Basically lots of risks according to situations.