You left your question unfinished. I have completed it in the way that I think you meant it. I hope that I got it right.
The reason that these firms can make high profits is because they are not in perfect competition. The main reason for this is that their products are not homogeneous. Perfect competition can exist in sectors like agriculture where one "Grade A" egg is essentially the equivalent of any other. This is not so in the computer industry. With computers, there can be real differences in quality. At the same time, there may be perceive differences because people see some brands as superior to others. Because their products can be differentiated, computer companies can make high profits where firms in perfect competition cannot.