Does it harm to study in one field and work professionally in another?

Personally, when you contact with more than1 specialization .
that will support you mentally and then you analyze correctly what is going on around you ....
out of my aggregate experience ; I've worked in2 different fields as a teacher of English concluded that most people don't seek mainly for knowledge but their main interest is the money then I dealt with merchants who made me shocked about the trade which depends on the materialism and don't feel with employees' needs .
the more you learn the more horizons will be clear .

Dear Mr.Fayyaz It is not harm to study in one field and work professionally in another, because each person have a specific skills witches can or can not be working on the same study line of his life.
My opinion that it is positively to take more experience Thank you Best Regards