It's become such a popular opinion that I wonder if it's being pushed.
Mitigation might be cheaper, but disasters that already happen have more clear incentives.
It’s terrible that we aren’t addressing issues early but it’s hard to see how we fail to adapt. At worst I think we see total excess deaths around two billion (which is a lot! but basically let’s us discount most of Africa and a few hundred mil from Asia and Americas).
We have less than 100 million people living a lifestyle that 7900 million people try to achieve. A few prominent people on the top blames it on the 1500 million or so, that have managed to achieve what most of us call basic decent living. Yes, the bar has gone up the last 30 years. Significantly. Yes, many would be fine on 1990-levels. Many wouldn't. The next 5 billion or so work hard to catch up regardless, and they're offsetting anything the smaller part does, by the sheer amount of growth. The poorest 1½ billion that's left are mostly trying to survive. The rest of us could have done _something_, but it's the ones who are worst off that'll take the worst blow.
I'm over 40, and learnt about this in school over 30 years ago. My grandparent's generation knew, and did nothing. My parent's generation are still struggling with basic things like throwing glass and metal in a separate container for recycling. The time for solving this with wonderful technological innovation has come and gone. We _could_ try to force some kind of return to sustenance farming, but previous attempts at such social engineering have ended in near-genocide. And so, all that is left is to deal with the consequences of deciscions that were taken long ago.
The good thing is that more and more people agree about climate change being real. We might have screwed up preventing disaster, but at least we still have a chance to dampen the impact.