Right now /r/movies is having a laugh about a scene from Rampage where a character hacks a corporate network through a thermostat. Much as I love a good chuckle at "Hollywood hacking", this is a thing that can actually happen.
I think the big difference between reality and a lot of Hollywood hacking is 1. the time it takes 2. how elaborate it always have to be 3. the fact that during the initial exploration they would most likely find an even easier point of attack.