Is profit theft?
Sure. I work my tail off to establish a business, from scratch. 10 or 12 hours a day, and many times more. Six days a week. For years. When everyone else is knocked off having a beer. Or asleep in bed. I give excellent service and products to my customers who demonstrate that by coming back regularly. I make a profit. And you call that theft. You don't know what you're talking about.
Your problem is that when you think you see capitalism you actually see the abuse of capitalism. Every economic system under the sun suffers from abuse. But understand this: it is not the big players at the big end of town that drive the economy. It is the small businesses, the guys that get out of bed at 5 in the morning to make a business work, who pay their employees fair wages and often take home less than their employees, they are the ones driving the economy, the ones who make it possible for us all to have a decent standard of living. They are the real capitalists!
Sure there are things wrong in capitalist societies. As in all societies. But capitalist societies are successful because everyone can have a go and build a business and give employment to others.
So get your covetous eyes off those who have money to excess. That's their problem, not yours. Have a go at building a business that actually gives people jobs, provides them with goods and services that are excellent. Then people will come and buy your products and services because they need them and yours are good. And you know what? You'll make money. And if you continue to give really good service, you'll make lots of money. And you'll know that you haven't stolen from anybody because you have given good service, paid your workers fairly, and worked your tail off, worried about the business, worried about your workers and their families, spent hours after your workers have gone home to their families getting it all ready for the next day... You will have the satisfaction of knowing that you've had a go and made it work for people.
By saying profit is theft you besmirch the hard work and integrity of the many thousands of small businessmen and women who are just out there having a go.