Invest that amount in some legitimate ICO, I hope you will get a good profit from there with your 7 BTCs, the other way is to invest in trade etc.
though it is really hard to know whether it is going to be legit or not, i think that it would be really hard to guess it, so i would be careful
Yeah its difficult to predict and trust here in online world, as we never know when it will disappear so investment should be made only after doing proper and higher level of research.