I think this is the right take. At the end of the day you just can’t change some people’s minds.

Arguably, you can’t change anyone’s minds, they have to change them themselves. You can try to lay the groundwork for them to make that change, but we all know what they say about leading a horse to water.

Like OP’s example of the uncle with lung cancer. The dude already has lung cancer, and is continuing to smoke, what more could you really say or do to convince him to stop? They’re already facing probably one of the biggest possible consequences of their actions and they’re still not stopping.

Sure, you could focus all of your energy into trying to browbeat them into stopping, but do you really think that’s going to get anywhere? Your time and energy are probably better spent convincing someone else to quit or not to start instead.