Back in 1989 my parents were looking to buy a home. We looked at Irvine but they thought it was too far from work (Cerritos/Artesia), so we ended up buying a tonwhome in Buena Park. It was sold in 2002 for 3x the original purchase price in "as is" condition, with termites.
So, yeah, had we bought in Irvine back then, we'd have made $, but it's not like you couldn't have made $ buying elsewhere. Irvine has always been more expensive from memory. When I started looking for RE in 1998, for the price of a brand new 2 bed condo in Irvine, you could get a new 3-bed in Placentia.
Now if I can find those old Oak Creek (Irvine) and Altura (Placentia) pricing sheets... they'd be real fun to look at. From memory, brand new 2 bed 1025 sq ft condo at Altura in 1998 was $130k, and plan 1 at Oak Park ( 1 bed, 869 sq ft) in phase 1 was supposed to start at $110k but I've never seen it lower than $140k back then.