You have these magical all-night coding sessions with just beer and music and you are getting so much work done.
Then you wake up later and later, eventually waking up so late and only needing to wait a couple of hours before you can start drinking again.
I was in a rut for a while, started staying up really late with absolutely incredible productivity and a feeling of not needed sleep. Flexible startup working hours was the ultimate enabler.
Then I got a headache that wouldn't go away, looked in the mirror and had huge lines under eyes, and I realized it's extremely bad for health and physical appearance.
I think people most susceptible to this are those who can't get easily out of bed in the morning, or take a while to get going with their day.
Nothing is worth irreversibly prematurely aging yourself for...people don't know though. It's a badge of honor but you pay the price.