OK, but I'm asking why they need a cryptocurrency. Paypal certainly doesn't need one.

Why does anyone start a cryptocurrency? To get rich, of course

this is probably the best answer OP is going to get.

i doubt there was much logic applied, past the idea of getting rich, to the few thousand crypto currencies that were born in the last decade.

Because you can't collect dumb money from dumb people with the pitch of "I'm starting a competitor to PayPal, invest in me."

But you can if you hint that if they buy your crypto tokens, those tokens will go to the moon.