You aren't going to get anything out of trying to prove them wrong. People believe what they want to believe and if you argue with them they will just get angry at you. And if you do prove to them they are wrong they will only get more angry with you.
You just pretty much summed up what's wrong with society today. Seems no one is receptive to at least being open minded and listening, or trying to find common ground.
In terms of broke family members advice? I don't havbe that problem, but I think sometimes it may jjust bethem looking for better advice?
And possibly them wanting "you" to inc=vet for tehm, so there's no loss on their part. I've run into this scenario a few times with friends.