Is hard work the key to become a millionaire? Or the exploitation of people?

Hard work, understanding the time value of money and living frugally will get you there. If you spend it as soon as you get it the only chance you have is hitting the lottery.
Being a millionaire in this day and age is not unusual, nor that rich. If someone was to give you a million dollars tomorrow it would not be enough for you to live out your life without working and earning more.