I still do not get basic premise - 'who does not care about money?'
The question isn't "who does not care about money?", it's "who would use BitUSD over fiatUSD and why?"
For me it is the same question with the same answer - everybody who cares about money. About 93% of the earths population.
And if you think that Ebay is the magnet for those 7% not interested in money/savings/yields/convenience/speed, I must disagree.
And IMHO no ebay user have to even know what bitUSD is. Even more than that, non of them should even know it has anything to do with cryptocurrencies.