When digging deeper into practices on how to be more ecological in software engineering, we ask ourselves why we are not doing it already at large scale. Well, as humans we sometimes act in irrational ways. The rebound effect is one of the most relevant barrier for us to not do software engineering more sustainably. Also, we see tremendouse advancements in efficiency of hardware, but overall no tremendous cut in CO2 emissions. Wirth's law is the empirical answer to that question.