Yeah, this is nuanced and for example people in US don't really have reasons to want it/need it. Also when everyone is on Bitcoin, then this won't be needed at all.
The main two cases I have in mind:
  • Someone operating business on low margins with a lot of money on the line. Volatility is the biggest enemy in this case, since the business can go bankrupt easily if the BTC value would swing down by e.g. 10% (and their counter parties denominate in fiat).
  • People in countries where local currency is rapidly inflating. Being able to switch to stable fiat is already massive improvement of experience and potentially human rights. It would be better if they switch to Bitcoin, but the stablecoin first step would imo provide a lot of value already.