Completely delusional. The fact that GT people actually believe these sorts of narratives explains why we're wandering in the desert the way we are.
Yeah, Atlanta grew a lot. What you're not noting is that 100% of that growth was due to transplants moving to the distant suburbs of Atlanta. Atlanta is a giant suburb, not a city. Some Purdue grad who moved to Marietta from Chicago was never going to care about Georgia Tech football. All the white Atlanta natives who may have formed a core of GT sidewalk fans left the city in the 70's and 80's (and would have ditched GT for the Falcons even if they stayed, as happened literally everywhere else in the country).
Sure, maybe we sell some more tickets if we stay in the SEC...to SEC fans. That model of building a program has done wonders for Northwestern selling tickets to Big Ten fans and Vanderbilt selling tickets to SEC fans. Northwestern is every Big Ten fanbase's favorite neutral site game to mix with a visit to Chicago and we'd be every SEC fanbase's favorite neutral site game to pair with a visit to Atlanta. We were never going to be able to keep eligible mostly-illiterate kids from the rural south, we were never going to appeal to the Bubba sidewalk fans that UGA has now, we were never going to appeal to transplants. From where you're looking, it must seem like an 18-carat run of bad luck. Truth is, the game was rigged from the start.