Work for an unprincipled property developer (Like Gladman Developments in the UK).
That will make you rich legally.
Morally, I'm not so sure.
Which legal work can make you millionaire very fast?
Engineering. Mainly computer and software engineering.
My typical hire starts off from $90,000 to $120,000 a year depending on their level of internships and side projects. They'll also receive a cash bonus anywhere from $20,000 to $100,000. Relocation bonus is $20,000. Stock bonus is around $75,000 to $200,000 in RSUs vested fro 2 years. These bonuses are given with the agreement that they stay with the company for at least 2-4 years.
So given two years, you're already about halfway to a million. In two years, if you're even average you'll receive a promotion adding another 30% to your original salary.