I'm torn in this. On one side, I think, with climate change and rising sea levels, living on a mountain can improve chances of survival. Of course, only for those who can afford. As for flooding on the low lying areas, the structure can incorporate a water reservoir to catch rainwater. The structure can also be designed to prevent landslides.
The inhabitants, including wildlife and flora, displaced will be the collateral damage. I'm not sure if it's worth it. How do you put a price on that? Is it even ethical to put a price?