While stable coins may be used like "a regular debit card", their actual real use is different:
* unlike for debit card, stable coins can be used without KYC (of course, in less and less situations, unfortunately)
* stable coins can be used for transferring value fast between different platforms. This happens (is settled, final) much faster than debit cards.

Stablecoins initial use was for traders, maybe even especially for arbitrage trading.
Nowadays many use it against Bitcoin price drops or other use cases adapted to their needs, especially no-KYC needs.



If you see stablecoins "like a debit card" and "like fiat" inflation makes fiat value drop, it can be also seen as inflating Bitcoin. That part cannot really be changed...