N’s conference costs $800, and it’s just membership and registration. Food and lodging and airfare are on top of that. Plus, he’s losing pay on the days that he’s there because his company is not covering it. And they are not covering it because they don’t want to lose him. He’s already over qualified for them, and this kind of conference widens the gap.
But he has to be paying these costs not only because he enjoys this kind of conference a lot but because that’s how one keeps oneself fluid.