Paypal denies to investigate because friends and family was used in all cases, because the considered the member a friend.
While I somewhat get that Paypal is not legally required to make people whole, I feel not even looking the case at all is neglectance.
The whole purpose of "friends and family" is that there's less fees but no protection. If you're buying a good or service from somebody, even somebody you know, you probably shouldn't pick "friends and family".
Paypal is just a tool to avoid giving your CC to a third party, never think about adding your bank account to your account.
If you don't like the free food, don't eat it.