There is no investment in bitcoin that is risk free the fact that long term investment is prioritise over short term investment doesn't mean that so long as one is investing in long term is a guarantee of success.bitcoin is best appreciated when view in terms of long term because short term investment involves high risk due to the volatile nature of bitcoin and also there is always greater potential of loss .
While not selling you will be risk-free - unless your wallet is hacked and you lose your coins.
I don't know why many people do it for the short term when we know bitcoin is not too volatile like shitcoin because the usual decline in bitcoin is usually negative news. But you should never be afraid of the decline in bitcoin because somehow the price will definitely recover again even though the process is long but because we are investing long-term it doesn't matter with this time part of patience while doing DCA all the time.