It’s simple, really: very, very close to major employment centers. Several business parks, from Del Mar Heights down on El Camino Real and High Bluff, all the way to Carmel Mountain Road south of 56, then the huge health care and biotech hub on Torrey Pines, then the huge computer and communication hub around Sorrento Valley. Many good paying jobs up there, and CV is the most convenient nearby bedroom community for all of them (quiet, safe, good schools, etc). There’s really nothing more than that.