It's not right all of are old coins no more profitable. Some of old coins are more profitable. I know every old coins are not more profitable. Some coins are good profitable.
I think that not everything, but the most part of old coins is not so favorable as new. Old coins already strongly grew and made many X. And new still can make and make them for you profit more.
It's quite odd both old and new has it's own potential when it comes into profitability they have both great terms for example
OLD COINS:
they can be more profitable because there are so long in the market but then it's upon on the coin use if it will raise in the market
New Coins:
They can be more profitable because they offer new innovative use for the unstopping needs of people.