I'm curious, too. Given that they have hundreds of millions of users and most (that I know) don't seem to care one way or the other about the privacy implications, I don't see usage being an issue at all.
Agreed, the network effect works seriously in FB's favour here. Do I add my payment details and get back the £20 an acquaintance sent me or do I wait until I see them and hope we both remember?
Once you're signed up then FB have dropped the barrier to making further payments with their platform, which presumably is the purpose of this from their point of view.
I've never really been on FB that much, so this may be fueled by that.. but i would hate adding my CC info to FB. Generally speaking i am very loose with my CC.. i don't worry about it too much, and give it out often. With that said though, FB (to an outsider) has had a history of sketchy FB apps doing sketchy shit with your data/feed/etc. This has seemed to install a distrust of FB and the FB-app ecosystem in me.
Not sure if that's common or not, and i'm sure i'm in the minority, but nevertheless i figure it's a valid thought. To be clear, i'm not saying that they shouldn't be trusted, i'm saying that to a FB-ignorant person, i'm not too trusting of them.
Note: This has nothing to do with anti FB/"FB data" type of people.
It's not that people won't eventually add their debit card
Your payee has to a) have the FB app installed, b) have a debit card, c) from a US-based bank and d) agree to add that debit card to the FB app.
It's more than just "pay on FB". Enough little hurdles to present immediate adoption friction. Many people know that you can do chargebacks on CCs but can't do that for debit cards so they have reservations about adding that debit card to online transactions (never mind that FB Pay is likely just using ACH in the background).