It is doubtful that there are any precedents for bad experiences in terms of bitcoin. As far as I know no one has suffered from short term investments in bitcoin. If someone is in too much of a hurry, it's a different matter. In the long run Bitcoin gives you greater protection of your principal. On the other hand short-term investing can cause your nerves to fray every moment. So everyone wants to protect themselves first.
maybe if you had been more specific on what you're referring to as short term investment I would have agreed with you but with my general knowledge and from the general connotation of short term investment, if you go about it the wrong way you will end up being in a big loss or not having the expected profit you desire.
for instance you started buying from January and intend holding for a short period of time like say six months, even if you started when bitcoin was at $38k and did your DCA for the period of six months with a weekly DCA of $150 which an average person can go for, and then Bitcoin price went high to $100k a long the line, would you be in profit? Absolutely yes, would you have accumulated enough quantity of Bitcoin, not at all. If we follow my analysis then you should have accumilated at least $3.6k worth of Bitcoin which wouldn't give you the expected profit you would possibly desire compared to making a long term investment. But what happens if you are patient and diligent enough to continue accumulating for at least four years? You would have accumilated $28.8k worth of Bitcoin which should put you at a good place in your profit region and this is the main reason why long term investment has always been preferred to investing for a short period of time. No one is against you investing using any time interval but being too short termed minded could be major distraction and could be to your disadvantage.