So I am Dutch and currently living in the Netherlands. I think it's something the Netherlands will definitely survive. As a general rule of thumb, a country can spend 50% of GDP for a few years - and end up OK afterwards - on something that's threatening the survival of the nation. The US spent 40% of GDP on WWII, for example. The Dutch GDP is almost a trillion dollars. I think that half a trillion dollars is enough to protect a small country that a) already has good water infrastructure, b) is only 42,000 km2 (25% or so of which is already water), and c) a lot of the threatened area is not terribly densely populated.

In contrast, Bangladesh's land area is ~150,000 km2 vs ~30,000 km2 for the Netherlands (figures off the top of my head.) Bangladesh's population is concentrated in places with extraordinarily bad water infrastructure and in the parts of the country most at risk for flooding. Their population is literally ten times larger... and despite having a 'low' growth rate it is growing at about two million additional people PER YEAR. Bangladesh's total GDP is also less than a quarter of a trillion dollars. To add to that, the Bangladeshi government is undoubtedly less skilled at leading massive public works and infrastructure projects to save 160,000,000 people (most of which live in poverty) from having their home flooded.

Put it this way, you have two choices. Choice A: you live in one of the wealthiest countries on earth, world renowned for its water management, and you're packed next to a lot of other wealthy people in a union with a lot of other wealthy countries. Your government says it will spend thirty thousand dollars per year - for every man, woman, child, baby, grandmother, you name it - to save your ass from global warming, and they have a history of winning against the water. Even if your country completely ceases to exist, you are bordered by two very wealthy countries where all your citizens have permission to live and work permanently, with no visas or administrative mess. These countries are big enough, and have faced enough of a population decline, that they'd each survive taking in 8 million or so highly educated, wealthy, English-speaking people with extremely similar culture and beliefs. Hell, we're so closely integrated with Belgium that we just peacefully swapped land! [0]

Or, you live in one of the poorest countries on earth, which has semi-friendly relations with a few other countries scattered around the globe. Your government says it will spend $400 - less than the price of a new smartphone - to try to save you from having your home wiped out by rising sea levels. This government's history of water management reads like a bad joke: their latest lauded efforts are to try to get water from a hundred and sixty kilometers away, and forty percent of the capital's population live in slums that regularly flood with sewage. The neighboring countries are all dealing with population problems of their own: they're also wealthier, and at least somewhat hesitant to take in one hundred and sixty million impoverished people.

I know personally I'm a hell of a lot more scared for Bangladesh.

[0] https://www.nytimes.com/2016/11/28/world/europe/belgium-neth...