The business case is clear.
A number of years ago, when people were first gathering statistics, mitigation was thought to provide a 2-to-1 advantage. For every dollar invested, you get two back. Now that number is 5-to-1, according to Swiss Re. See Lessons from extreme weather events: What disasters teach us about resilience.
As noted in the article, disasters are not isolated to just the United States. it is a worldwide issue. Poor countries likely don't have the funding to invest in mitigation and the larger, wealthier countries don't necessarily embrace the benefits. It will take a "series" of major disasters to get policymakers, here and abroad, to change their thinking and their budget priorities.
Claire Rubin, as is the case many times, shared the link above.