There is nothing deader than the past. What you have done or who you were before, is unimportant. Usually, the past just leaves you with a shaky argument with which you maybe able to justify your arrogance with (you know who I am? Know what I have seen and done in my life?). At best, if you were bit luckier and were blessed (or cursed) with a good memory, the past leaves you with the bitter taste of a lot of old mistakes, called "experience". But it really don't matter. Who you were, and what you've done, is of little importance to me.
Who you are now and what you can do today is what matters.