I've always realized what a huge advantage I've enjoyed my whole life, by being in the lower part of the upper middle class. I would just call myself upper middle class without the lower part qualifier, but lots of multimillion aires, David Letterman is an example that comes to mind, call themselves upper middle class instead of rich.
That also speaks to a different point,
class, behavior in society, the way you take care of your property and treat others, is more a function of your upbringing than it is of monetary wealth. Many people who came from the lower classes and have suddenly acquired fame and wealth continue to exhibit the behavior of the class they came from. Britney Spears, Snoop Dog, etc all continue to behave in a low class manner from which they came.
All of the above is not to say that many good law abiding people in society don't start out in a lower class and then end up 'making good'. However as a general rule though, even middle class and rich criminals tend to take good care of their property and not do petty crimes and acts of vandalism.
Its very hard to leave the class one is born into, very hard to generate the income that establishes yourself as middle class, without the advantage of having rich or middle class parents to get you started.
So now directly to the question poised in the OP, I believe that there are not many people with the means to move from a high crime area who do not. Also in most areas, even those considered
bad, you will find enclaves of wealthier people, business owners, etc who have added security and who are excluding
undesirable types, by the amount of rent they pay or purchase price of their homes.
So at the end of the day the people who are living in high crime neighborhoods and are good and decent people who have the social skills to 'fit in' with a higher class, most probably are lacking the funds to move, not the desire. So my advice to them would be to get more education or training so as to try and raise the funds to move.
One final thought remember class is more a state of mind than it is of monetary wealth, but having a pocket full sure doesn't hurt.
As far as me personally, another fellow upper middle class boy, Jim Morrison said it best in the song The Changeling.
I live uptown
I live downtown
I live all around
I had money, and I had none x2
But I never been so broke
That I couldn't leave town
Im a changeling, see me change x2