Why do movies about Ancient Egypt, Roman or Greek mythology always tend to be so shitty?

I'm talking about movies like Gods of Egypt, or Wrath of Titans, Clash of Titans, Percy Jackson 1&2, Hercules The Thracian Wars, Immortals, or the recent Troy TV show and so on.I mean these cultures have some of the greatest stories in all mythology.How does one studio after another completely fuck up? via /r/movies http://bit.ly/2UEU8gp