Porn stars are usually amongst the higest rank in depression-
The investigative pluto 1st houser that I am, I've investigated this. Porn stars all have debilitated venus and mars planets. Venus is in Scorpio, Virgo, Aries, or Capricorn, and/or aspecting saturn. ( unrequited love) . Mars is in air (mostly libra) followed by gemini, then aquarius. or Mars is in Virgo. Also Mars squaring venus shows up a lot too.
Venus in a mars sign indicates lust but also selfishness (Scorpio and Aries) and Capricorn is restriction and physical lust, and virgo is work.
Mars virgo can indicate sex as a means to an end and not really for any intimate gratification and mars in air signs sex is detached.. air is objective and free flowing.
Karrine "Superhead" steffans while not a pornstar, is an example of what manifests here , she has venus and mars in libra.
Anyway a debilitated venus is a sign of potential depression in and of itself.
To get to the original question why do men watch porn. Pornstars embody all the lilith moon (darkside) fantasies that most wives and girlfriends will not put up with I guess. Or just plain ol variety