Would it not be more correct to say that the opposite of irrationality is, well, rationality? This is important because rationality is something I assume we agree is a characteristic of humans. Humans can't help but be rational, which is why irrational behavior can be the exception that proves the rule. To say "being smart" is the opposite suddenly creates a a somewhat unscientific rift among human animals, doesn't it? But I do get why you want to say that for your argument, but you should be a little more nuanced in order to get one over on me. Not that I am particularly smart or anything, but just because I am listening to what you are saying.

But otherwise, I think I see what you are saying, but why is living a long life the goal for you? That is a somewhat novel argument in this context.