Because when new bull run will arrive there will be new shitcoins and your shitcoins will end dead or delisted from exchanges which can lead to 100% loss.History is always repeating.
5,5 years old chart:
Interesting chart to see coinmarketcap from 5 years ago. 5,5 years old chart:
I agree it's always important to question a coin. Some coins are only hyped and will crash in price finally.