Perhaps part of the issue is that we are so used to inflationary currencies, like dollars and euros, where your money loses value as you hold on to it.  That gets us used to the idea that we must do something to counteract that loss in value.

Maybe you would be better off thinking of Bitcoin as similar to shares of Google stock 10 years ago.  What would have been the wisest thing to do with those shares back then?  Gamble them away?  Loan them to strangers on the Internet?  Trade them for lower quality stocks?  No, you would be best off just holding on to them and letting them appreciate in value.  Or accumulating more and holding on to those shares, as well.

Bitcoin IS the investment.  You don't need to further invest the investment!  Jous HODL (hold on for dear life, no matter what happens to the price).