The choice is not only judged by hard factors like available wealth, education, area of expertise but it is also influenced by soft factors like - personality - acceptance to uncertainity and risk - lifestyle - family values
There may be people who are very happy with their jobs and cant get the same lifestyle even if they do a business. And I dont mean in financial terms but around factors like family life, peace of mind etc.
Some people are much more accustomed to risks and uncertainity, as if they dont get a kick if everything in life is pre-planned and covered.
So in fact I think it is a very personal life and lot more goes into this decision behind hte covers and not only what comes to our brain.