If you don't really need them now.
Bitcoins are themselves the best form of investment.
Their worth has increased drastically with time .
I consider bitcoin to be better than share market etc.
The first bitcoin ever to exist was not even worth 1$.
And now in just 8 years it has crossed 1000$ mark.
So I insist you to keep them with you and use them when you require.
Tgat is correct, the best way to invest Bitcoin is to keep it in Bitcoin and hope for the prices to increase persistently so that you can sell back for profits when it stabilizes.
Well maybe not the best way, we could say the safest way. But there are a few moonshots, a few projects in an incubator right now being born, If you jump on one of that train(s) you could get 10 fold returns in a relatively short time (two three years) . Remember that there was Ethereum, NEM, Dash, Monero, Gamecredits and couple of others that exploded in value in a few years, not just bitcoin. But sadly we could only dream what will be the next moonshot
That's true but how do you determine the moonshots early enough in order to take maximum advantage and that 10 fold return in two or three years.