Why would you want to use crypto as payment system?

I know adoption is adoption. But why in the hell would someone want to use crypto as a payment system? Now i understand why people back in the days used Crypto as a payment system on Silk Road. But what i don’t understand is using crypto as a payment system for every day activities.

First of all why would you want to pay with your Bitcoin/Ethereum instead of fiat? Isn’t using fiat,credit card or debit card much more simple and fast?

Second i know what Gwei and Satoshi is but it’s still gonna be hard to track what you are actually paying:

+Can i get one cup of coffee please? I’ll pay with Bitcoin

-That’s gonna be 0,00011 Btc sir

+???

-???

And finally we all know crypto is volatile. One day you’re gonna pay 0,0048 Eth for a BigMac Menu and then the next day you might pay 0,0055 Eth

Considering these facts, what are the reasons for you to support crypto as a daily payment system? What is it that i don’t see?