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.
Surprisingly some coins from this chart are up from then but volume on exchanges is low,so holders of these coins are truly bagholders.
From that list, only bitcoin and litecoin that still survive in the top ten and the other replace with the new coins like ethereum, eos, bitcoin cash, bitcoin sv, tron, and the rest is the old coins like ripple, stellar, tether. The market still changes in every year, and some of the coins in the future will also change again, and we will see the list will replace with the other coin but bitcoin still on the leader of the cryptocurrency. And for now, I think many of the coins trying to compete for each other because they want to get a better position in the coinmarketcap so we will see a new changing again in this time.