Congratulations, you just demonstrated the irrationality he was discussing.
He pointed out that giving the $10 will *SAVE* you $1. That's a net *gain* of $1, not a net loss of *anything*. Something that saves you money costs you *less* than the alternative, not *more*.
He didn't say "net" and "save" is only a useful word when there is a net loss. Words mean things. If you're saying that giving someone $10 means I get $11 in return later, then that's a 10% gain, and worth something. Giving someone $10 so that I can save $1 is ludicrous and an obvious net loss.