Stablecoins steal some of those users from third world shitholes who need to escape their home currency, which is something the dollar itself had always done.

But if you are confident the dollar itself has a finite number of days as the global reserve, then those stealing are also temporary as those those same tether holders will flock to Bitcoin when shit hits the fan (e.g. tether rugpulls that are happening get more coverage instead of getting covered up)