I would say so. Unless they were high school sweethearts, most celebrities think of themselves as akin to royalty, and dating or marrying someone "common", or without immense wealth, fame, prestige, or beauty would be marrying beneath them. Shudder to think.
Naturally, when they age, and the cameras and paparazzi are no longer interested, e.g. Elizabeth Taylor, or they need someone to wipe their behinds for them, then they'll consider coupling with "nobodies".
They dont always, Toby Mcguire didnt!
Probably because they are always around othr celebrities and they socialise with other celebs more than other peoeple.
Other people might also be starstruck so they dont get to knwo them proprly.
Other celebs are the only other type of people they really hang around. Many though marry before they become famous, so their spouses are 'normal' people. Also other celebrities also understand their lifestyle