If you want to trade bitcoin then you can choose large and reputable trading floors such as floor trading floor has many strengths and safety for the trader you can find trading with the floor and you Can be assured when trading here
Your question is not clear. People are confused as I, because there are different comments on bitcoin investment. Any way I think that if you mean that where to invest bitcoin, so investment itself is investment and no need to invest it anywhere. If you mean where to invest the earnings of investment then you have many options in regular businesses.