For example it's much easier to convince people that it's OK to cut certain parts of the budget when no one has seen some of those programs used much in a couple of years. Events like this make it clear that preparations for extreme storms, even if they're not common, are still necessary.

Now of course most of what Trump has "done" is PROPOSALS to the budget, so he hasn't necessarily changed anything yet. But it still seems like a reasonable time to discuss these kind of issues.

And the government involvement in flood insurance, basically subsidizing people to live in areas that are a lot more dangerous than necessary.

Let's quantify a once in a lifetime event just a little bit:

Let's say it's a 'hundred-year' event which means that it has a 1% probability of happening in a given year. And let's say that the event costs what Katrina did[1], i.e. ~$100 billion ($100,000,000,000).

That's an expected loss of $1 billion every year.

Once in a lifetime events like really bad hurricanes hitting a particular Gulf city aren't exactly 'unknown unknowns'. And furthermore, major damaging hurricanes in the US total (not just a single city) happen every 5-10 years maybe. It's absolutely worth putting a lot of resources into risk reduction (hazard assessment, long-term resilience efforts, disaster planning and strategizing). Ignoring this is shameful, especially considering that hurricanes are the costliest disasters the US faces, and efforts understanding and preparing for 1 once-in-a-lifetime event like Katrina will substantially apply to an independent once-in-a-lifetime event like Harvey.

And political will is the only way that things will get done in an appropriate fashion. It's not exclusively political/governmental (for example, reinsurance companies invest in research into this and their results plinko down to local insurance rates) but governments are in the best position to coordinate efforts, enforce regulation (zoning etc.), and have both bigger assets and bigger liabilities than everyone else.

[1]: https://en.wikipedia.org/wiki/Hurricane_Katrina