Sorry, sdr, but it was not “newbies” who gentrified San Diego, or any of the other cities. Gentrification happened because of a social-cultural-political backlash against suburban sprawl, and the wreckage of the beautiful, historic buildings and sites in these urban cores. Many people favored urban living, and decided to halt the decay, and began improving urban cities. Oftentimes, politics played a large part in the gentrification of urban areas.
A growing population does NOT necessarily mean that a neighborhood is “gentrifying.” It could very well mean the exact opposite.