Privacy. No need for any transaction details to be given to my bank. Just use BTC to buy cash, exchange for prepaid cards, for instance. (Or direct BTC->cards.)

Since it's hard to use BTC anonymously, Z Cash allows nice insertions of hard privacy points.

A person I met a few years ago told me rather proudly that he refuses to use banks because the courts can use the money in his account to pay his child support when he doesn't want to.

This is probably a huge market given the number of those people I have run into in small towns. Another is tax BS with the IRS where they try to garnish but person can't afford a lawyer to show it's bogus. They seem to have trouble doing it with things other than regular, bank accounts. People getting payed on cards often have no trouble.