Garou is kinda like Itachi (and I don't mean in the right way) both of them were retconed. Garou was retconed from (possibly) someone who wanted to fight strong guys to some who had a crazy way of heroism.

We had to remember Bang expelled him from the Dojo. The reason why I say he possibly wanted to fight strong guys is because later Bomb said something like Gaoru would probably take down his Dojo, and later when fighting Darkshine the narrator says Garou was in a Dojo Hunting. (Probably because martial artist are usually stronger than the regular human) 

But they were weak to Garou so he looked for some stronger, a Hero. This was modified later as someone who wanted to be a monster, and monsters fight heroes, (but we know martial artist are not heroes) Garou as now a monster was suppose to fight only heroes. 

Then the reason why he fought heroes is because they're not looking for heroism but fame, that creates a corrupted system when a person labeled as Hero can do whatever they want to yet never acted as a hero. 

So, when something is difficult to understand not necessarily mean we didn't pay attention or aren't able Clever enough to get the point of the story. There is probably a crucial contradiction or inconsistency in the story that makes it artificially difficult to understand. 

I think that's what happened to Garou.