I do think there is a generational aspect to this, and not just in that my generation (Gen X / early Millennial) hasn't witnessed the effects of these deadly diseases, but that we did grow up in a time when a lot of big companies and government scandals were exposed.
When I was growing up we learned that Big Tabacco had been hiding the full extent of how dangerous cigarettes were for decades. We grew up when Big Tobacco was still marketing to kids.
When I was growing up the full extent of the CIA's experiments into LCD, etc were released (and this wasn't conspiracy)
We learned about just how corrupt and misguided Vietnam was and watched while the US went into Gulf War II on a lie.
We grew up with lakes and rivers being polluted for decades by companies who just didn't give a shit.
Gen X/Millennial's are an extremely cynical bunch, we've learned you can't trust the government or big business to have your best interests at heart (hence the ongoing obesity & climate change crisis's).
And a little bit of cynicism is fine, we shouldn't blindly trust people in power.
Unfortunately, the result of so much exposure to corruption and so much cynicism is that you start to see it everywhere, even where it logically makes no sense (moon landing deniers, flat earthers, anti vaxxers).