Or they die off. Which (having grown up there) is infinitely more likely. Their smart kids leave. The one thing they do that's smart is put all their resources

Or they die off. Which (having grown up there) is infinitely more likely. Their smart kids leave. The one thing they do that's smart is put all their resources into their 'smart' kids (which may not actually be the smartest ones) and then push them into an environment that encourages them to make something of themselves. The main side effect being that they're no longer satisfied by nothing and leave.