> Just look at the Nano cryptocurrency for example: 0 fees and <1 second transactions. You can send 0.00001 dollar or 9 billion to anyone in the world at any time. All you need is a phone.

Sounds great! But why can't we just use that technology to move our existing money around? Why do I have to trade my USD for NANO, transfer the NANO, and then trade the NANO back to USD at the other end?

Why wouldn't I simply engage with a bank that lets me use the same open-source technology to simply move the USD from one place to another? I don't want to become an investor in Nano just to transact any more than I want to buy PayPal shares to use PayPal.

We can and do, they're called stablecoins. It's not possible to send fiat around unless you digitise it first, and this needs to be done in such a way that it's impossible to mint more in the process and such that this is verifiable by everyone - hence (most) stablecoins.

Edited to add: Also XRP is used as a bridge-currency to automagically do what you described, but with XRP in place of NANO. This is a product that due to regulatory uncertainty is not widely used yet, but it is still offered to, and used by various banking and payment firms who have signed up for it with Ripple. It's been hampered by the SEC in the US, but is still used elsewhere.

Mastercard is a payment support platform. They take the burden off of the business owners and let them focus on their business instead of the minutia of interfacing with the financial system. That doesn't go away with cryptocurrencies. In fact it might be more needed than ever as there are now multiple payment networks with lots of intricacies such as coin storage, keeping track of transactions for taxes, etc.

Visa and Mastercard are likely still going to be important in the future just for the sheer fact that business owners will take at least a decade to update their backend stack to be sophisticated enough to handle the various payment APIs, UX problems, etc that crypto brings. With Visa and Mastercard your existing PoS terminals still work (now with crypto) and you can continue focusing on selling books or groceries or whatever else you do instead of being a financial systems engineer.

People can pay with their phone using a simple QR code. Merchants can check on any computer with a web browser.

How complex does Mastercard make it right now?

Like I said, it's a dinosaur ready to go extinct.

That's from an end users perspective. From a merchant's perspective if they provide that QR code they now have the additional burden of custody of a bunch of crypto assets which means learning about, installing, making a specific bank account to sell the coins, dealing with tax burdens, etc which is a lot of work and risk for someone already overworked and stressed by their primary business.

Or they can just use a payment network like Visa or Mastercard and not have to worry about any of that. You pay with BTC or ETH and the merchant receives USD. Everyone's happy. The merchant doesn't have to hire an additional crypto-specialized IT person or spend 6 months diving down the rabbit hole like we did. They just run their business.

Sorry, maybe I'm just ignorant, but since when do Mastercard and Visa handle taxes and everything you describe?

In this case it would be their ability to prevent you from having to deal with crypto taxes since you just receive USD like normal.

All businesses have accountants to figure that out.

Yeah and those accountants charge by the hour. Crypto taxes take up a lot of hours (and that's if your accountant already knows how to deal with crypto). The vast majority of small businesses don't have dedicated accountants and having to pay for the overhead of dealing with crypto is not in their already strained budgets.