I don't think you can go so far as to say doctors are guaranteed a job, but there is a reason that the UK has special categories in the Tiered points based Visa system for doctors and nurses. Not enough Britons are going into medicine and nursing, so they have to make immigration easier to attract foreigners to fill the need. Perhaps the explanation for the shortage is that the terms of endearment in the UK medical system are ****e. Of the many UK medical professionals I have encountered, I'd say the vast majority are in it because it is a calling, not because it is financially lucrative. Pilot wannabes would be well advised to treat aviation the same way or prepare for early burnout and disillusionment.