It happens all the time in life. People like us hang out with people like us. Those people hang out with those people.
How about: Those people live over there.
There are understandable reasons why this happens with property. Cost is the obvious one. Wealthy people buy or build more expensive homes, which increases demand, making surrounding properties more expensive, so only wealthy people can afford to live there.
We could view this as market forces. Or we could see this a potentially an example of our natural tendency to want to hang out with people like us, and be afraid of people who aren't like us.
It is important to spend time with people who 'get us'. And people who are like us are more likely to "get us" as well.
But we lose by limiting our circle of friends. At some level, we can all 'get' one another. We're all people! But understanding someone who isn't like us requires more effort, skill, practice and personal awareness than smiling, nodding, crying and laughing with someone like us. We personally miss out on growth when we choose the easy road to connecting with people.
If our neighbourhoods are filled with people who look like us, how much of life are we missing out on? What would need to change?