"you paid HOW MUCH for a BIKE?! You've spent how much on tubes, tires, saddles, pumps, getting "the perfect" setup? You're insane and stupid. Think of what you could do with that money!"
"I've spent less on cycling this year than you've spent on diabetes management."

edit: Similarly, somebody in the clyde forum said, 'well, it's cheaper than being sedentary...' which is absolutely true.