There is no upper bound here. The eradication of smallpox is money saved and suffering prevented every day for as long as humans are around.

Border screening clearly has a high failure rate, our recent experiences with this should be fresh in your mind. Besides threatening public health domestically, outbreaks in foreign nations are nevertheless a major economic liability. If COVID had never left China, we would still have seen a huge worldwide disruption, for example.

And anyway, screw them, we got ours is a shit perspective. Empathy should be part of the conversation when talking about so much suffering and death.