For Homero to describe that list of items he stole from the house as "petty" just shows how much he believes he is entitled to take whatever he wants and any complaint can be dismissed as being unwarranted or petty-minded.

It doesn't occur to him that if he owned that house and a tenant had walked off with all those things he wouldn't exactly be passing it off as inconsequential.

The narcissism is strong in this one.