I think it's less doubling down, and more that a thousand died and many more thousands left, then people probably moved back for jobs as they reopened, and could be a lot of people who weren't there before.
Just googled and there really is a sharp population drop from like 500k to 250k after Katrina... I mean, wtf can you do if your job and home is destroyed? You have to leave whether you like it or not.
And then if jobs exist somewhere, people will move back if rent is cheap and jobs exist. Sometimes you don't consider these things permanent until you're still there 10 years later.
So many in the Bible belt don't believe in climate change. It's half their fault, half billionaire's fault and modern propaganda. If you don't believe in it and think it's some liberal lie, then yeah, why wouldn't you say fuck it and move back to hurricane alley? And if you do believe in it, well, does it matter if you still need a job and apartment and this is where you found it?
You can't fault people for surviving IMO. Most people just get stuck surviving where they have a job and place to sleep.
New Orleans isn't home but it's one of my favorite cities in the US. So much good food, fun culture, really nice people... It's a lot to give up, even if you have to.