How to know they are not? Till now, there’s no test being done to observe the time gap between failures on computer parts considering how frequently the user gets into the case, there’s no observed data either way. People that don’t do much to their computers their computer last for several years where others who often modify their PCs apparently end up replacing faulty components every now and then.

Silicon devices have ESD protection built within them, effective enough to lessen those lower-voltage ESD events. HDD are protected by the metal casing surrounding them. There are several things that one can do to reduce the chances of damaging the parts, and a lot of people do some of it unintentionally while working.