You did not lose it, the only loss is when you decide to sell. If you did, you should learn that the cryptocurrency market is volatile, and you must be confident that the price will return to that top again, but the question is when?
There is nothing safe, so if you want zero fluctuations then use stable currencies, but then you will not achieve profits.
As for some safe strategies, they are DAC where you buy a certain amount of Bitcoin whenever you have a surplus of money at a fixed time and for long periods.