I will deal with both responses at once: Capitalism is the accumulation of capital through the maximization of profit. It’s inherent tendency is to eliminate competition either through monopolization or versions of price fixing. It is great at gathering capital that can be used to generate more capital. This is a type of specialization and worked very well when infinite growth can be assumed.
The basis of capitalism is greed. In the early 18th century much of the discussion on this system was concerned with the use of “private vices (greed) for public virtues (growth of wealth in the society)”. Could the advocacy of greed be justified if the capital produced was used for public benefits. That seemed to work for the first couple centuries but then it became increasingly obvious that it brought more problems than it fixed.
Human societies are successful when they achieve the broadest possible well being. Greed is was always a sin because it is selfish and destroys well being for a growing part of the population. If income grows for all people allowing for differences of reward then the system works. We know now that capitalism cannot support that. A small minority gains enough capital to live off the income from that capital without work. This is the process that destroys societies and leads to predatory, final stage capitalism openly dedicated to exploitation of the population. Thomas Piketty explains this in detail in Capital in the 21st Century.
The final question is if capitalism is possible in a a functioning society. It cannot survive without close governmental regulation to prevent it converting into a massively destructive force ruled by a tiny oligarchy.