That #2 is a partial quote from Shakespeare. People quote the first half a LOT to justify being selfish, but always leave off the second half.
This above all: to thine own self be true, And it must follow, as the night the day, Thou canst not then be false to any man.
In other words if you change your principles to please everyone you'll wind up in trouble because different people want mutually contradictory things, but if you stick with what you know is right you will not do them wrong. Some of them may be unhappy with you, but at least your conscience will be clean.