A weak person cannot take from others because they do not have the power to. As to principles, while you may not like how someone else acts, but everyone lives by certain principles, whether they realize it or not.
With decency, again, that is a matter of person opinion; Starfox's post and the subsequent responses have made that abundantly clear.
Oh, and it's rather ironic that you speak about treating others with respect in the first part of the sentence, and proceed to do the exact opposite one phrase later.
Need to be a bit more specific methinks.