Because to claim that bitcoin succeeded as a payment/salary method is ridiculous. Vast majority of bitcoin volume is just speculation on exchanges. The massive price volatility is a testament to why it cannot be used as a currency -- who would want to make a services/job contract that in a matter of a year could change its value by an order of magnitude. The whole point of these contracts is to hedge against future volatility. Remember, if bitcoin goes up then the employer gets screwed, if bitcoin goes down then the employee gets screwed; there is no direction that is good for everyone, only stability is good.

Furthermore, good currency should encourage investment (into things) which means it needs to be (slightly) deflationary (to introduce a cost to not investing into production). Otherwise you get into a paradoxical/toxic situation where NOT producing useful things becomes financially advantageous.

You're arguing for a demurrage currency, not a fiat, debt- leveraged fractional reserve one.

I am arguing against bitcoin, not for something. I definitely am not arguing for fiat.