We should not attribute to malice that which is more easily explained by stupidity.
When something goes wrong that affects us we tend to associate this wrong doing to someone who is doing something that is out to harm or get back at us.
The great majority of the time, they aren't out to harm us and their action is simply a mistake.
Since the majority of the time these actions are a mistake and not an act of revenge or malice toward us, we are better off thinking these are a mistake because of probability and because of wasted time.
If we think that someone's actions are an act of malice toward us then we will spend all of our mental capacity being angry at the person and planning revenge.
This will take up a lot of our effort, time and focus.
If we simply understand that 90-95% of the time someone's actions aren't intent to harm and are just simply a mistake then we will be much better off mentally.
An example from my life with this mental model was when the super in the building next to me had an elevator company remove a bunch of weights that were on top of the elevator and load them in their truck on a weekday around 7 AM.
The slamming of the weights as they were put into the elevator company's truck woke me up and the noise prevented me from falling back asleep before I went to work.
I then yelled at the elevator company and the super before I left for work.
The next day there was a car parked outside my building with an alarm that kept going off every 2 minutes.
I first attributed this to the super parking his car in front of my building "to get back at me" and setting off the alarm on his car every couple of minutes with his car key.
Knowing about this mental model I quickly attributed it to stupidity not by the super, but to the person that must have had a broken car alarm.
Had I not known about Hanlon's Razor then I would have spent a lot of my time and focus probably planning revenge on the super instead.
It turns out Hanlon's Razor was correct as I haven't heard the car alarm or seen the car on my block since and if it really was the super's car it's likely that I would have seen the same car parked on the street.
And even if the super told someone to park their car with a broken car alarm in front of my building to "get back at me" then who cares anyway? Because if I knew this then I could have possibly started a war by trying to get back at him but intsead by treating it as stupidity instead of malice the issue goes away due to me not reacting.
A more common example of Hanlon's Razor is road rage when someone cuts you off while you're driving. Although it is easy to attribute someone cutting you off to them trying to cause harm to you, it's more likely stupidity on their end because they didn't plan enough time for travel so they are now in a rush to get to their destination.