They don't have a use because we as app and website developers can't accept Bitcoin because no one has any Bitcoin!
Not really. They don't have a use because regular money serves the market just fine.
There are apps you can't do with fiat because the users don't have any fiat!
I just told you the developing world is our fertile ground.
There are other apps you can't do with fiat, because you are not allowed to. And this problem will be growing more pervasive. For example very difficult to get Paypal or Amazon Payments to accept certain business such as dating sites, selling precious metals, etc..
WhatsApp supposedly collects $1 per year (plus more for "extras") from hundreds of millions of users via mobile payments, app stores, or whatever. Likewise countless mobile F2P games that collect lots of money.
There just isn't a big mass market hole when it comes to payment services that crypto can jump right in and hope to fill.
yes there is. It is in the developing world.
If you do have a great idea for a social app, a game, or whatever, you should just launch it using app store payments and make bank. Crypto is a waste of your time.
I have a great ideas (and others do too) but can't monetize them because the billions of people in the developing world have lots of energy and time but no disposable fiat and/or at least especially NO CREDIT CARDS!
You entirely missed the elephant in the room. Crypto was supposed to be for the unbanked but no one is even trying to distribute to them.