Optimistically, they solve consumer micropayments by allowing the unbanked to send and store money via WhatsApp.
Life pro tip:
If your Charles Schwab broker emails and says that they're wondering why your retirement savings are nothing but medical marijuana penny stocks and if you'd like to come in to talk about healthy portfolio management strategies, you should go into the local office and not ignore that email.
International transactions - Venmo is very limited in this regard.
The unbanked - As stated already, there are about two billion unbanked people worldwide.
Avoiding banking cartels. - We've fed these parasites enough, don't you think?
Ease of use - A payment over a social network would be relatively seamless, particularly if you believe that apps allowing for rapid transfer between cryptocurrencies will be feasible (they are to some degree already).
It should also make paying domestic staff and various contractors easier, and that’ll be nice.
If cash were invented today, it would be illegal. For most small payments if not large transfers, in the USA consumers actually have the right to transact anonymously. Tracking micropayments publicly forever on a blockchain seems like a step backwards. Being able to track large transfers on a blockchain is one of the benefits of living in the world where the Byzantine General's Problem has been solved.