Timing and long term planning

My beloved son( he may know that in 10, 20 or 50 years time), discussed with me the topic of entering Medical school.

Who want to study to be a medical doctor? His friend ( name optional with consent)tried 6 years with interview. thought of entering medical school for more than 10 years.( may be less crave during childhood with view of relatives working as white coat hero)

Anyway..One may try even after completed first degree...say Bachelor of science.
The question...How to know a candidate has true interest to work as doctor in the future?
It is true it could be cultivated. With more exposure and understanding fot he subject.
Is it true medical doctor earn alot of money? How about politicians, Banking managers, Wal street investers, computer scientists...haha....yes...quote Bill gates
So why find a tough job with shorter lifespan..( true, your beloved doctor died earlier than the norm in this world...got statistic and other proof.

Can doctor earn a reasonable amount of money to keep up with further upgrade, children's education..and food..( ha...food business earn more than doctors)

My nephew, Dr. Mountain Reserve( literal translation of his name) got an offer last week from one of the rishest country in the world...he is going to get 300,000 a year salary with hope of double in a few years. sound good ? prepare to work and continue doing tough surgical operation for 18 hours looking at a poor fellow's brain.

Yes...Presious brain.( You have brain...we all have one) So...think