A good way of expressing the answer to a good question, Seasoned.
Of course, implicit it in the notion is the concept that the chance has to be something worth taking a risk for in the first place and that is, I think, a key determinant over whether we feel regret from not taking a 'punt' at something.
For example, as Seasoned said above, a regret that has followed me all through my life is that I did not join the Navy when I was of age to follow my own wishes rather than being constrained to obeying my father (who forbade me when I wanted to join up whilst still under his roof). That was a chance I have ever regretted not taking - but of course there is no going back now.
Whereas, the decision I took not to follow a career in the risky business of trading in stocks and shares I have never looked back on. Walking away from the job I was offered, even tho' I had no other to go to at the time, was a right choice (despite the fact that it has meant that I have never made any significant money) as it means I can still look myself in the eye when I gaze into a mirror.