For altcoins it is very important to have a developed ecosystem. Altcoin must have a lot of users and a big community.
It must be simple to buy and sell altcoin and it must have a good liquidity.
It is very good that there are services like
https://www.koinal.io/ that allows to quickly and simple to buy altcoin by bank card.
The more simple to buy and sell altcoin more users it has.
It is simple to buy only Bitcoin and altcoins with big capitalization. For other altcoins it is necessary to use cryptocurrency exchanges. But it is good that their are services that allow to by altcoins directly from the cards, but they must have a big choice of altcoins.