Day trading hasn't worked for a long time, it's proven to make you lose even during bull runs. Holding is the only thing which has been able to win out, why NOT follow it?
OP is just looking at things from the perspective of the trader,it makes no sense for him to just hold coins if you can profit with them.But in reality there is a very small percentage of those who can make profit on a daily or monthly basis.A good part of those who trade mostly rely on luck,one week you have good profit,other week you loose all you earn and even more.
For most people holding is safest way,you just need to store your coins in best secure way-trading can be a very lucrative job for those who know what they are doing.Also in trading there are additional risks,keeping coins in exchange(hack of exchange,phishing),sending to exchange/back to wallet(the possibility of sending to the wrong address).