I'd pay with fiat, which I prefer anyway. Bitcoin is an asset, and a mechanism by which you can transfer value across many miles, very quickly. All your points are "what if's". The reality is that people are saying bitcoin does have value. If businesses didn't accept it, there would still be people trading it, just like in 2009 when no one accepted it. Could it drop to zero? Yes, it's possible. But your argument seems to be that because it could become worthless, it IS worthless. That's not true.
What is the point of calling Bitcoin an asset when it is so obvious that it is not. An asset is defined as a resource with economic value that can provide future benefit. Bitcoins are just numbers on the internet and you can't eat them, drink them, wear them, drive them, sit on them, enter into them, please the aesthetic senses with them,... nor do they represent legal rights(like fiat does) which ultimetly lead to goods and services with the properties just mentioned. Thus, Bitcoins on their own are completely useles with regards to benefits and that's why they aren't an asset.
The difference between numbers on a bank account and on a Bitcoin address is like the difference between numbers on an utility bill and numbers on an empty paper. If you don't pay the bill, you will get a legal notice for non payment of the bill from the company lawyer and further a case will be established against you. Hence, numbers on an utility bill have legal power. Numbers on an empty paper do not have legal power. The same is true for numbers on a Bitcoin address - if nobody wants to accept them in exchange for goods, services and fiat, no legal case can be made to get some kind of value out of them - meaning, they possess no legal power. In the case of numbers on a bank account, if nobody want or accept them in exchange for goods and services, those who received the loans would not be able to repay their debts and a legal case would be established against them, so that those who recieved "the numbers on a bank account"(those with deposits) can be settled in some imovable or movable property.
As we can see, fiat is an asset in its true sense - an asset with the legal power that can be used and exchanged as a true market value. Bitcoin on the other hand is... NOTHING. So, people are buying 'nothing' with the hope that the price of 'nothing' will increase. Clearly, this is an antithesis of market exchange and the definition of an irrational behaviour.