It is not easy to establish the authors of viruses. A number of groups have been identified as potential creators of them. To my mind the reason pushing people to do such senseless work is still the same: an inferiority complex, sometimes combined with mental instability.

Hackers: Hackers (McAfee and Haynes. p.38) are people analogous to drug addicts. They seek novelty and new experiences in producing viruses.

Freaks: This is an irresponsible subgroup of hackers. They have serious social adjustment problems and often have a general grudge against society. There are several reasons why they write viruses: Some do it for fun, others for money. Some of them may be mentally distressed, sick of their life and want to hit out.

Students: The technical ability necessary to write a virus within the reach of a computer science student, who may see such a project as an intellectual challenge
Disgruntled Employees: It is possible that virus attacks may come from disgruntled employees. Their motives are often vindictiveness, revenge, or extortion. These may accompany a strong sense of moral duty making disgruntled employee, in his own eyes, a freedom fighter.

Computer Clubs: Some clubs have been very active in providing their members with information on how to write viruses.

Terrorists: Terrorists (McAfee and Haynes, 1989, p.11) are fanatics, for whom nothing else matters. They may have been indoctrinated from an early age and are loyal to a group, which holds them in very high regard. They are, in their own eyes, modern-day martyrs.