Macbook Pro: Hibernate vs Shutdown
Interesting question. Computers have a measurement call MTBF or mean time between failure. The more parts something has, the shorter the period between failures. If the computer is off, then it cannot fail during that time. So you will extend the life of your computer by turning off the power when not in use. Hibernation is still on, and helps conserve battery power. Since your disk is not spinning media, shutting off power to it will extend its life. CPU failure will be due to overheating, so if the fan is not coming on when you boot, it is in no danger.