What if Gotham is the pump?
Like. What if, because Gotham is such a shitshow, anyone looking to improve their lives has their eye on being able to move out of Gotham, so whenever Bruce Wayne's charitable endeavors come somebody's way, they take it, pack their bags, and move the fuck away, and take that money with them.
Meanwhile there's an ongoing influx of people to Gotham primarily because they're flat broke and real estate in Gotham is dirt fucking cheap because it's a shitshow, and there's always places hiring because 1) they've got Bruce Wayne money to try to make a difference, 2) there's no shortage of places that need to be fixed up a little, and 3) villains are always in the market for new henchpeople.
So you're a broke millennial from any other town in the country, and you have student loans, a job that hasn't kept up with inflation, and your landlord has raised the rent three times this year so far and it's eating up two-thirds of your paycheck. You look for housing on the internet and discover that one-third of your paycheck will get you the mortgage for an actual house in Gotham, a house you own and will never have to deal with your scummy rentjacking landlord again. And Wayne Industries is hiring, and so are sixteen different disaster remediation places, and six staffing services with a sort of weird vibe to them but they offer benefits, since when do temp agencies do benefits, and sure the crime rate is high but the rest of the world's heading in that direction anyway, especially if you're homeless, which you're gonna be in like four months if that jackass your landlord raises the rent one more time, so get in losers, we're going to Gotham!
And you settle into your bigger-than-expected apartment and get a job that brings you a comfortable paycheck and you learn to live with the terrorist attacks and the explosions and the gunfire and the neighbors and the drunken billionaire swimming in the restaurant fountain, and you pay off your student loans, buy a car, suffer a few months' unemployment when your boss goes to jail for trying to assassinate the mayor and then your partner loses their job for a few months when the office gets smothered in a jungle's worth of climbing plants and you develop hospital bills when you both get caught in a hallucinogenic terror gas eruption at the mall, but hey, you'd be homeless by now in any other city, so you live with it.
And then it's a few years later and you're wanting to start a family, but the neighbor three doors down owns pet hyenas and the park was firebombed last week and someone froze all the water pipes and you crashed your car into one of the impromptu ice sculptures and you'd really like your kids to grow up in a normal city where they don't have to receive advice like "don't talk to strange plants."
So you visit one of the social work offices and get yourself a bit of assistance, save up your money, sell your house for the price of a down payment to the sort of incoming fool you were six years ago, and use your polished resume to get yourself a job someplace that doesn't have What To Do If Clown Attack on their safety training syllabus.
You came, you left, and Gotham remains. A shithole.