it is a very idiot way to use all the money you have to invest in cryptos, crypto market is very fluctuative all the time, so even a good trader must be affraid of choosing to trade all their money or not, because in cases the price of a crypto can makes trader become million in a night or loosing all if the price to the bottom, so that is why many traders give us advice to split into the money many parts to invest in many cryptos.
I do not think it is an idiotic thing just to place all of your money in one coin because many people are full time take part in trading so he/she can still maintain their crypto as well, so they can trade it easy way. And not all coin going to give you good profit too so if you just focus on one coin each time, you will tend to get profit gradually and of course bigger than if you diversify it