I agree about survival, but how much profit is enough? Please! Don't start with supply and demand or Econ 101.
You must be a liberal democrat, this line of thinking about when people have "enough" is an incredibly dangerous road to go down as almost everyone has "enough". There will always be people living in cardboard houses on the street, eating scraps from restaurants or soup kitchens. Why do you get to make more money than them? Why should they go hungry when you have so much? Surely you can afford to give them food, money, and clothing considering your profit margins on your work is so high. Besides, there are competitors in your line of work that have a smaller profit margin than you. Why should you make more than them when their margins are good enough?
The problem with what I've sarcastically stated and what you genuinely stated is that those who have the power to decide what is "enough" or "fair" never have your best interests at heart.
You should really look into where your mentality leads.