There is only one really meaningful light-bulb joke:
Q: How many psychiatrists does it take to change a lightbulb?
A: Only one, but the lightbulb has to really want to change.
The last few decades have shown that developing software is hard and costly. Repeated surveys highlight overruns of 75% to 100%, cancellations and unsatisfactory results. These figures are well known, and haven’t changed, indicating either we don’t know how to “fix it” or aren’t willing to change. Since there are some industry segments and individual organizations that do seem to be able to deliver on-time, on-budget, there must be a method that works.