My question to be clear is why do we all need to learn java or .net(C#) , still java or .net are more popular than delphi or c++ and even there are lot of resource,articles or books compared to c++ or delphi about java and .net. However, I heard majority, if I am right about 80% of software are developed using c++ or delphi in the software industry. so, why do we bother about other languages specifically about the cosmopolitan languages such as java or .net in education as well as for job interview.

Although, still I know the elegance of java and .net, their safe code execution,fully objected oriented behavior ...etc, but still according to the statics they are not preferred on software develpement as a primary language mainly because of their execution time compared to c++ or delphi. So my question are why do they choose them for jobs or educational purpose and everything else? why do we lose our time learning these language if we are forced to use the other languages in the industry?