And not just cancers. Look at the intro paragraphs to the Wikipedia article on Epstein-Barr, for example. It's like every year we discover a new link between it and some horrible disease. My mother has disabling neuropathy from Sjögrens; there's now some links between Sjögrens and EBV, and she has measured EBV reactivation.
In COVID, we discovered "Long COVID", and how disabling it was for victims. Not just Long COVID - e.g. obvious sequelae - but also a whole slew of other diseases (particularly cardiovascular and respiratory) have their probabilities shoot up dramatically in the six months post-infection, lesser increases after that. Yet as we started comparing it to other contageous diseases such as influenza, we started finding that even if SARS-CoV-2 is somewhat more at risk of causing debilitating sequelae (times how everyone was contracting it at once), influenza and other common viruses are also very capable of causing debilitating sequelae.
My father went from someone who was going on long hikes every day to prepare for hiking to Everest Base Camp to being unable to walk in a matter of days. He caught a virus on a plane, "got better", but then a couple weeks later, suddenly ended up in the hospital becoming rapidly paralyzed due to Guillain Barre. It nearly progressed to his lungs, but he was lucky to avoid intubation and to be an unusually-fast recovery case. Most aren't so lucky.
Just because you "got better" doesn't actually mean that you "got better". Pathogens deliberately disregulate your body in a vast range of ways (some in weird ways - for example, measles can cause your body to "forget" how to fight other infections that you were previously immune to!). Your innate immune system attacking them means deliberately doing damage to your body in the process. And the adaptive immune system runs the risk, with every infection, of accidentally learning to attack some part of your body instead. Even the very act of the immune system proliferating is itself a risk. Because of my mother's Sjögren's, the immune system was attacking her salivary glands. This led to extensive, nonstop lymphocyte propagation. Which in turn, led to MALT lymphoma. Your own immune system's activation can cause cancer.
It honestly shocked me that we went from all we learned during COVID to "pretending that nothing ever happened", just back to exactly how we were living before. No, we should absolutely not all be masking all the time. But can we at least clean our damned air, like we clean our water? Yes, if you're up close talking to someone, you should be able to get infected from them if they're sick; trying to prevent that is too difficult. But the person across the room should not be getting sick. You know what it reminds me so much of? The Broad Street cholera epidemic. It's well known that removing the handle from the Broad Street pump cured the infection, a victory for modern epidemiology and proving the hazards of contaminated water. But what's lesser known is the fact that as soon as the epidemic subsided, they put the handle right back on. People simply didn't want to think about the fact that their feces was leaking bacteria into their drinking water supply.
Also, to be clear: pathogens are not Pokémon: you do not need to catch them all. Yes, if there is no vaccine for a given common "mild" pathogen, it's usually good that children catch some variant of it once as a child, rather than first encountering it when they're 70 years old. But you do not need to catch every seasonal variant that goes around. Memory B and T cell immunity against severe outcomes is very durable. A virus shuffling up its receptor binding domain to evade immunity enough to cause a seasonal infection doesn't mean your body has to start over with learning how to not end up hospitalized from it.
