I suppose this also depends on what you consider 'default'. Who says the default should be to stay in one place for decades? Leaving and staying each have advantages and disadvantages, but as far as I can tell neither has proven to be generally the 'best' option.

In fact, my experience is that those who do move around generally seem to lead a happier and fulfilling life, but that's just my experience perhaps.

My point is that staying behind for 'stability' could be equally selfish. Uprooting your life in itself is not selfish, however the way you do this could make is to.