We don't have a surplus of carriers. We have a shortage, at least relative to their current tasking. They're overstretched and behind on maintenance. This is unsustainable so the civilian leadership will have to either cut back on missions or build more.

There’s always an argument for more equipment, but you need to start building them long before they enter service and need to set budgets long before any specific crisis.

Funding for Nimitz was authorized in 1967 they started construction the next year and it was in service in 2025. The US has a very large and very expensive carrier fleet today because people decided it was worth having X boats a long time ago and they calculated X under the assumption that a significant number would be spending time docked / on the other side of the planet from where the conflict is.

Obviously, part of that equation was based around warfare and the likelihood of losing some / extending deployments etc, but what we want today has no barring on what we actually built as all those decisions happened a long time ago.

TLDR; Having more than strictly needed for normal operations = having a surplus when something abnormal occurs.