I think long term investment isn't advisable for now because of the current state of the crypto market being volatile. However, I would say it depends on the project and what the investors want. I believe there are still some coins out there which are profitable when you hold them for long term.
Each person will have different investment plans and long-term investments are still encouraged at some good coins in this market. I don't object to your opinion but all of these coins depend heavily on the upcoming trend so any of our predictions can be wrong. Currently, the crypto market is very volatile and this makes people face a lot of big disadvantages so more care needs to be taken in trading.
Of course the uptrend will be back soon so consider choosing some good coins like Ethereum because I believe one day you will make a huge profit from long term holding.