I don't know the particulars of Canada at the moment, but I doubt it gets as high as you think. Maybe it can get to 100K (Canadian?) dollars plus night shifts, but you can only do a limited number of these (for legal, logistical and practical reasons) and there's the fact that, well, you're spending whole days at your workplace. I doubt very much the final "average" earnings get beyond 150K, and those are gross earnings. Substract taxes and cost of living, plus debts and insurance when applicable (US insurance rates are ridiculous). Having a little business on the side won't earn that much either, at best it will qualify as an extra wage (at the cost of having an even longer work day), and it's not really an option for everyone. No specialist will make "millions and millions" of dollars, that I can guarantee you. Some plastic surgeons might have somewhat big incomes by virtue of keeping private clinics, but for every one who got lucky and pulled that out there are a hundred who didn't (and in fact, in the US the average plastic surgeon does not earn that much). This is pretty much a constant in North America and Western Europe (present company excluded because here a doctor makes half of what he would earn elsewhere in Europe/America). I specified "first world" because funnily enough the earnings-compared-to-cost of living do skyrocket in Iberoamerica, with bonuses for those with West-Europe/America training (even then it falls short of "millions and millions". Very short)
Don't believe me? Just google it around. Or, if you don't feel like googling, just check medscape. They keep a yearly table of the gross earnings (and job satisfaction) by speciality in the US