2-3 years is not a fast time although this is a pretty good thing but my advice you must be good at choosing which coin is right to be stored for long period of time. keep BTC and ETH for the time as long as the price is still at the highest level because crypto is unpredictable for a long time. so in my opinion better you immediately exchange coins that you save with USD when the price is down. this I think it is quite safe to do because storing too long will also increase the risk level is high enough.