In a way its true, but it fails to take into consideration that many if not all of the coins that exist today could disappear in the current meltdown and follow-on from a Tether/Bitfinex collapse. If you are holding some of the coins that do survive, ten years from now it will indeed not matter what you paid from them. They will be money and you will spend them directly on goods and services, and you will be very, very rich.
Of course, you would be much richer and much safer if you had waited to buy until after the fraud scheme propping prices of bad coins collapsed. Much safer too, as you would have a better idea of what coins are good and what coins are bad.