There's a difference between "getting rich" enough to be able to retire and handle health issues and building an empire.
All of the possibilities you mention are much more likely to be handled by
a) Good budgeting
b) A solid career as an employee or an independent contractor
The reason to start your own business is because you want the challenge, and the satisfaction of building something important.
If you have a desperate need to have a few million in the bank, your best shot is to to get a good job, learn about investment, and start living cheaply.
All of the possibilities you mention are much more likely to be handled by a) Good budgeting b) A solid career as an employee or an independent contractor
The reason to start your own business is because you want the challenge, and the satisfaction of building something important.
If you have a desperate need to have a few million in the bank, your best shot is to to get a good job, learn about investment, and start living cheaply.