Why isn’t CPU time more valuable?

We might need hundreds of hours of CPU time for a simulation, then nothing while we figure out what to do next, then another hundreds hours to run a modification. You can rent CPU time from Amazon for about 2.5 cents per hour. Surely it should be possible to think of something for a computer to do that produces more than 2.5 cents per CPU hour of value.

Source: www.johndcook.com