Why Paypal holds your money and marks it pending

Both Paypal and Fiverr like to hold sellers money for a long time.  You may have marked an item as shipped or electronically processed and Paypal still shows it as pending even though the buyer confirmed receiving it.  It originally said 21 days until it is released but if I mark item as shipped then it will be reduced to 14 days which absolutely makes zero sense.


The only reason I can think of Paypal or Fiverr holding peoples money this long is so they can earn interest on it.  The longer they keep it in their accounts the more money they get.  Paypal is essentially a Bank and abides by same rules as other banks.

What Paypal did to me when I sold a website to a person is the equivalent of a bank that process credit card for a store holding their money for weeks or almost 1 month.  That makes absolutely no sense and Paypal should change this.