This is true, but I think a rational person would rent in this scenario?
The key thing is whether their belief that this property will be under water in 50 years is their actual belief, or if it's performative, or if they are experiencing cognitive dissonance where they 'believe' it in one context (what they say) but don't believe it in other contexts (like managing their finances). Again this is extremely common, people 'believe' that prayer works but also only rely on it when they lack practical solutions like taking Motrin, and the few people who really believe in the power of prayer are treated like they are mentally ill (for example when they refuse medical treatment for their children) by the very people who claim to 100% believe in the effectiveness of prayer.
Distinguish "really believe in the power of prayer" from believing that prayer is the only thing you should do. See https://en.wikipedia.org/wiki/Parable_of_the_drowning_man
This is just cope to try to find some coherent position to avoid dissonance collapse. If prayer works you should just use it exclusively.
The funny implication of this stupid parable is that God has become more effective at answering prayers exactly at the rate and in exactly the ways that humans have no longer need him Him to be. The ancient god of the bible had was powerless to cure cancer, but in 2025 he cures cancer all the time - via chemotherapy.