Nowhere. Come back in a decade. Anyone who tells you otherwise either lucked out with one of the astonishingly rare exceptions that didn't fail and wasn't run by psychopathic teenagers or, far more likely, they're trying to con you out of your btc or be sucked into their own deluded investment fever.
And plenty of people will probably suggest gambling. Amazingly enough this is not considered a valid avenue for investment on the rest of planet Earth.
I still don't understand how people can suggest gambling!
I mean come on guys, you do know that the main principle of gambling is that the bank always win no?
But still people gamble and try to build strategies and things like that... That's dumb as hell. Gamble if you want, but don't expect to "break the rules of maths" and find a safe way to gamble. You will lose in the end. It'x just made this way.
I also don't know why do people even recommend gambling to other users. Gambling is just a way to lose your money and not an investment at all.
For investing bitcoins, there are no trustworthy websites as all promise to give you a good profit but at the end there is a high risk to lose the investment. Since bitcoins are itself not recognized, the investment opportunities also have the same fate.