First, your A-B situation is not a reality for most of engineers. Second, if you want to dedicate 10 years of your life to work, make money and retire early -

First, your A-B situation is not a reality for most of engineers. Second, if you want to dedicate 10 years of your life to work, make money and retire early - it's a reasonable choice for many. But if it goes into 40s - why do you need money, if you would not be able to enjoy it constantly working? Your money may go straight to doctors and psychotherapists eventually.