Here is information about people that have become millionaires.  I focus on the statistics instead of my opinion.

My information comes primary from The Spectrem Group.
http://millionairecorner.com/Content_Free/Surprising-Job-That-Gets-Many-Americans-Into-the-Millionaire-Club.aspx

The average United States millionaire is 63 years old. Just 1% of millionaires are under the age of 35, and 38% of millionaires are 65 and older.

Here is an additional source:

Wikipedia
http://en.wikipedia.org/wiki/The_Millionaire_Next_Door

For more information on how to create a business check out the SBA.They have excellent resources for starting a business.
http://www.sba.gov