The best way to fight the world's problems is to start at the source. If we let the "free market" decide everything, it will inevitably favor the ruling class, those with power, money and influence. Don't have money? Sorry, can't be a part of it. And of course, the market panders to the ruling class, which is often made up of certain groups of people, and the working class, made up of another group of people.
Upward mobility is difficult when the system is working against you because you can't contribute enough. Becoming equal with them (like if you're non-white, female, LGBT, etc.) is hard when the multinational corporations pander to those who can buy the most, the ruling class.
After all, people are naturally selfish, and capitalism allows them to indulge in greed because it's the market that decides what is made, and often what the government will provide and for who.
It costs money for a business to do things for the workers, like safe working conditions, a real living wage, reasonable hours, and also to be sustainable for the health and welfare of the planet.
It wasn't capitalism that gave us the 8-hour workday, the weekend, safe working conditions, the abolition of child labor, the right to vote for blacks and women, equal rights under the law for all races and creeds, or any of that stuff. It was the people united against the tendencies of capitalism that gave us what we so needed.
Interesting video of a speech by the political scientist Michael Parenti of why capitalism doesn't work for most people: [link]
(Skip to 1:26 to skip the introduction.)