Ah yes, because this problem is independent from any other problems such as robbery, car break ins, homelessness, drugs, etc
If you scale that 200k for cost of living it shouldn't be very hard to find an alternative
That is, if you're making a $200k salary in NYC, let's say you spend 50k a year on housing and 50k a year on other expenses, but the rest you can put towards savings.
Then you move somewhere that is 50% cheaper, but you make 50% less. So now you can get the same quality apartment for $25k and your other expenses are only $25k, but you're only saving $50k a year instead of $100.
Obviously this is a gross oversimplification, but the vast majority of time if you move to a place with a much lower cost of living, your reduction in salary, if looking at local jobs, is unlikely to make up for it. Never mind the fact that for many industries there are only a few places where you can live if you really want a career: if you work in high finance or fashion in the US, you probably want to live in NYC. Film or TV, you'll be in LA, etc.
What percentage of New York makes over 200k? They can stay, the rest can leave.
IOW, it takes all sorts to make a city work, and if you have labor (those people who work, at whatever wage) move away because the policies favour non-labour (those people whose income is from theft) it doesn't really matter how many 200k stockbrokers want to stay - they'll have to move eventually too.