With all of the time I have, I am an insult to the dead.
In context, the person is saying they feel like they are wasting their life and that innumerable people in the past would've killed to have the kind of free time or life they have.
It reminds me to be grateful for both the time I have alive and the quality of that time.
I find it extremely motivating in pursuing my various personal pursuits. I should seem like a Renaissance master to the people of the past and anything less is insulting.