I hate to say this but to use the only quote from Jimmy Carter I'd ever use, he once opined "life isn't fair". The bright medical student who longs to be a surgeon, but has 10 thumbs simply is not going to achieve his/her desire. There is more to being a surgeon than simple manual dexterity. The hours suck more than any other specialty with some variation, and the training is both longer and more brutal than other specialties. You also need to be good at doing physical examinations and diagnosis, just as much as the non-surgical specialties. In any case, trust me when you are good at what you do, have a family is NOT the time you want to go back to do 2-3 years of residency training in a new specialty, and then start at the bottom.
Most doctors, surgeons or otherwise, choose their specialty based on interest, training time, lifestyle etc. Of course, income can play a part, but one of my nieces who is a doctor, and quite good, told me at graduation that she had very much enjoyed the surgical specialty I practiced (still working at that time) but she had seen my lifestyle since when she was quite young and that was not for her for a variety of reasons.