Good point, but what I meant were the smaller actions like suddenly turning on other mutants at critical moments that don't make sense. His ideas to eradicate humans to protect mutants made sense as "I'll achieve my goals by any means necessary" is his M.O.

One of the ones that bugged me the most was in First Class. They are trying to prevent the humans from being able to acquire and exploit Mystique's DNA, so immediately after preventing her from being captured, he decides that it's best if she dies to prevent that from ever happening. This logic can be justified, but he decides to accomplish this by shooting her in a location the humans control, in essence spreading her DNA everywhere and presumably leaving her body behind for them to exploit anyway.

It completely defeats the purpose of everything he was working towards and negates what he had just accomplished. It was those kinds of inconsistencies that bug me.