[relativ575]

SLS flight cost is $2B. Each launch. Did you forget to include the decade prior? It's so expensive that it can fly no more than once a year. The next flight is scheduled for Sep 2025, three years after the first flight. I bet you think that isn't absurd.

SLS use leftover engines from the Shuttle era. Yet it still cost 160 millions. Each. Thrown away after each flight.

Vulcan is a conservative design with no reuse. It also uses BE-4 engine, which costs them nothing to develop.