I know that this is not the answer you're expecting and you've explicitly stated that you don't want to do, but the best thing to do is to move. By staying there, you're contributing to whatever is bad there.
If the problems could be fixed by individuals, someone else with much better reach and opportunity would most likely already have done so. I'm sure the problems are much bigger than what individuals or even big groups can do to fix, mostly because of the size of the city.
By moving away, to a better one, you're draining away resources that it feeds on. At some point, the city has to fix its problems... and with most people gone, it's very much likely that the problem becomes much more manageable for individuals and small groups.
If the problems could be fixed by individuals, someone else with much better reach and opportunity would most likely already have done so. I'm sure the problems are much bigger than what individuals or even big groups can do to fix, mostly because of the size of the city.
By moving away, to a better one, you're draining away resources that it feeds on. At some point, the city has to fix its problems... and with most people gone, it's very much likely that the problem becomes much more manageable for individuals and small groups.