Why do we do self destructive acts?

If we saw someone jump off of a roof, flap his wings and try to fly, we would never try to imitate it. So why is it that we see people do destructive behaviors and suffer the consequences and yet we still do these destructive acts.  The reason is that our Yetzer Hara will always give us reasons to legitimize something that we strongly desire.

Adapted from "The Spiritual Self" by Rabbi Abraham Twerski