Well, we see people and even political groups laughing at the idea of a virus outbreak that kills 100k even today, isn't it?
Now picture it without the benefit of hindsight.
Why did western society failed so hard at containing the virus when countries like South Korea were already leading by example at the start of Q1 2020.
Also, South Korea has very much not contained Covid. They've relied on fairly strict social distancing measures to stop cases outright going exponential, but those cases are still there and all indications are that an increasing proportion of infections have been going undetected since the start of the pandemic. (There's no way of knowing the exact number because they don't seem to have any program to measure the actual infection rate, unlike some other countries, and their level of testing is frankly pretty poor compared to the western world these days.) Those measures are also no longer sufficient, with cases reaching new record highs most days for the last week or so.
Firstly, why would someone laugh? Pandemics with a 100k death toll are a fairly regular occurrence, even in modern society. OTOH if you said 1M + most of the world under some form of home quarantine, lockdown or travel restrictions for well over a year, that would have been laughed at.
Second, it's hard to attribute deaths to climate change directly. Natural disasters kill people every year. Who can say with absolute certainty that the death toll in this or that incident would have been lower if not for climate change?
Third, on a longer timescale climate change absolutely has the potential to kill more people than Covid.