A penny a day sounds severe, but if I figure at 34 I have 50 years left, that's only $182.50.
Yup, that's another way to think of it. So at age 34, if you're gonna live to be 84, then your $100 expenditure really costs you $282.50. If made at age 75, the $100 expenditure only costs you $132.85.
The 18 year old who spends $100 of his first paycheck for some frivolity, really spends $340.90.
Or one final other way... at age 57, things cost double. At age 30, things cost triple.
And I totally agree that this type of thinking will eventually lead to madness! But it's a really fun and interesting way to play with the numbers. It also turns me into a cheapass scrooge.