Cash is only partially fungible?
No. I need to make x amount to live, and anything more than that, will go towards luxuries/retirement/investment etc. I can't afford to take money out of what I NEED, for what I WANT, but this isn't money I need, it's out of budget. 11/12 months, it goes to savings/investments, but once a year or so, it goes towards a luxury that I may not have been able to afford otherwise. I completely agree, cash is cash. I had an opportunity to replace my car with a nicer (fully loaded) car, for the same price, or get the same one (newer model) for cheaper. A bad decision (assuming you live paycheck to paycheck) is to get the nicer car. I opted not to, and saved the $, even though my budget allowed it.