As a nearly empty nest father of six I find myself relating cloud economics to home economics. When my family lived at home we shopped at wholesale stores. The idea was that I could get massive quantities of something for a lower per unit cost, thus saving money on the overall budget, even if a little bit would sometimes go to waste or spoil before it could be consumed by the ravaging teenagers. This compares nicely with the pre-defined public cloud models. With these models you pick from pre-packaged configurations of servers that might not fit exactly what you need but it will work, usually leaving you with some amount of un-used CPU, RAM or Disk that goes to waste.