Actually many altcoins are widely accepted in the world, such as litecoin, ethereum and even bitcoincash or ripple, as many people prefer to use altcoins to carry out fast and cheap transactions, something that is quite difficult to achieve through bitcoin.

However, most altcoins are much less popular than bitcoin because they are relatively newer. If the bitcoin is making great efforts to make itself known internationally, the other altcoins are still much less known, so it is difficult for them to displace the bitcoin in terms of its universal acceptance.