You got me curious, so I did the math for us.

I am a drip coffee person, drink far too much coffee (40 oz) throughout the day, and work on a fairly large corporate campus so I have easy access to hot/fresh coffee that I can purchase. Even though there are multiple branded places to get coffee from on campus, they have similar pricing.

• Small (12 oz): 4x @ $2.65/pop = $10.60/day
• Medium (16 oz): 3x @ $2.95/pop = $8.85/day
• Large (20 oz): 2x @ $3.25/pop = $6.50/day. This is obviously the cheapest choice, but will result in a cold bottom half of the cup due to drinking my coffee slowly vs pounding it

My wife and I split a pot of coffee. It takes us 3 oz of coffee beans to brew it. I can buy a 20 oz bag of the coffee beans we use for $15.29, which works out to $2.30/pot. We often stock up on the beans when they go on sale, but I don't know what we paid for them the last time around.

So.. since my wife also drinks coffee let's say that the price spread between purchased already brewed coffee vs brewed at home coffee is between $6.50-$10.60/day. Splitting the difference = $8.85. Doing that 365 days/year = $3,120 saved.

The fact that I have coworkers who drink a similar quantity of espresso based (more $$) drinks at work is insane.

Do this over a 25 year career, invest the money monthly ($260), plan for a conservative 5% rete of return and you'll have $162,577 - only half of which is principal.

Apply this pattern of thinking over a number of different spending categories and you'll be way better off financially. That said, the stats on the billionaire class are eye watering and no amount of frugality will catch any of us up to them.