That is where you got it wrong, you did not lost money because bitcoin went down in price, you lost money because of your own decisions, now you are looking for an asset to invest in which there is no risk, let me tell you that such a thing does not exist and you are never going to find it.

Now if you want to lower your risk this can be done but it has to do with the portion of the capital that you use on each trade, the solution is simple reduce the amount of capital that you use on your trades and in the case you happen to lose you will lose less money, it is quite simple and yet this is not something many people like to do as this reduces their profits as well.