It's easy to believe you're invincible in your twenties. Or "later me can deal with it.". As that later version of me, I'm not a huge fan of that earlier version in a lot of ways. It's fine, I'm who I am for what I went through, and I'm righting the ship. But the more cans you kick down the road, the more you have to deal with later and the harder they are to deal with. Physically, mentally, financially. It's ok to try to live life freely, but definitely be aware of this and consider kicking one less can every chance you get.
Nothing, they're not genuinely interested in a discussion. They're just trying to pin you with a bad answer and will keep moving the goal post until they think they gotcha.