I honestly think GT fans are just miserable people sometimes. If we could get behind the team with the same enthusiasm that we use to boo the refs, we might actually have a home field advantage. Combine this with lackadaisical Greek/student turnout and it's a recipe for malaise.
Anecdote: I used to have seats in upper north, and there was a guy who sat close to me who always found a way to be negative. We could be up in a game by 3-4 touchdowns, and he'd be pissed that we let the other team score. Some people just can't enjoy good things.
The phrase is something like "We're Harvard during the week and Alabama on Saturday". Been a long, long time since we've been Alabama on Saturday and I think the average fan needs to realize this. Remember the other team is fielding 85 players too and didn't just show up to get rolled over.