Fame and recognition are some of the factors that push scientists/investigators to engage in scientific fraud. For some others it may be out of sheer opportunism, laziness, greed and or pressure from significant others.
The definition of scientific fraud is wide and there is no accepted standard definition of it. However, there is consensus on what is not a scientific fraud. For example, an innocent mistake should not be regarded as fraud. Fabrication, manipulation of data, plagiarism (the use of part or whole of another person's work without acknowledgment), falsely accepting credit for intellectual content and   non-disclosure of conflicts of interest are the commonly reported scientific fraud.