Why does the rattlesnake rattle? Why does the dog bark? Why does the shark bite? Because it is in their nature, it is hardwired instinct. Hillary Clinton lies because mendacity is one of the main building blocks of her character, an automatic defense mechanism like the skunk and its anal scent glands.
In the latest example (which may well have been overtaken by other lies in the last 24 hours), Chris Wallace catches Cankles wagging her forked tongue again: "Mook Admits Clinton Lied About Claiming FBI Letter Was Sent Only to Republicans".
Unrelated update: Joe Biden is lucky he's not riding on Hillary's airplane - "If [Trump] wins, I’ll extend a hand,” Biden said. “He would be president of the United States of America, period. I pray that doesn’t happen. I want that [Maniac? Pathological liar? I wonder what he was actually going to say - Paco] — I want Hillary to be president, but whomever is the president is president of the United States of America.”