I seriously doubt Bitcoin fees are less than PayPal
EDIT: I just checked and the bitcoin transfer fee over the last 3 years was about $1-2, but it has been around $10 the last 3 months. PayPal charges a $2 fee for a $30 payment. The difference is a lot less than I expected.
Oh, and Ruud is a sysadmin of the lemmy.world instance, not a Lemmy dev.
EDIT 2: Ko-fi seems to take a 0% fee on one time transactions.