Then you have not thought hard enough.
The reaction of politicians to an epidemic which, unchecked, might kill half a million people in the UK and has probably already killed over a hundred thousand people in the US is that, if letting more people die will improve their chance of keeping power then they will do that: they do not care, at all about anyone but themselves.
So what do you think their reaction is going to be to climate change: a problem which, unchecked, will kill billions of human beings. But those human beings are future human beings: they are children now or have not yet been born. And, quite probably, most of the people who die will die in poor countries: there will be millions of deaths in the US and the UK, for instance, but only millions or tens of millions, not hundreds of millions or billions.
And the great majority of those deaths are decades away: only quite small numbers are dying now, and the politicians will be dead and gone by the time the death rate really climbs.
Do you think they care about that? Do you think they will do anything other than posturing? Of course they will not. They are entirely happy to do nothing about an event which will probably mean the end of a recognisable civilisation on Earth: they simply do not care because caring would mean they have to do something which might damage their own power and prestige, today.
This is the way civilisation ends: the narcissists and psychopaths we have chosen as leaders will destroy it because it is convenient to them to do so.