CO2 footprint is irrelevant when considering personal cost savings/expenses from bicycle use.

I like to eat good food, two pizza slices are much better than one no matter what it costs in cash. I consider any activity that allows me to eat more food without gaining excess weight as adding "value" to my well being, not a negative cost. If you don't enjoy eating, that is your issue.

I don't think writing checks for insurance provides the same personal pleasure for most people, nor do most people derive any pleasure or satisfaction from sticking a gas nozzle into their car.

I agree that many bike commuters overestimate their cost savings, since the fixed costs are not significantly reduced by the relatively few miles ridden by the bike commuter. The cost of the gas saved is chicken feed. The only variable commuting cost that bike commuting can really save on is expensive downtown parking in big cities. The only significant savings comes when family bike use allows the owner to reduce the number of cars owned.