People who do things they know are wrong will always conjure up an explanation that absolves them of any culpability. They'll even believe it themselves.

For example, people who steal office supplies from work always have a good reason they tell themselves.

For another, all the people who post on Hackernews justifying cheating in college. My favorite bullshit excuse was cheating was justified because the professor didn't expend much effort with countermeasures.