Computer viruses

Who writes computer viruses?To whose advantage computer viruses are written?That's the first use of computer viruses - as a sort of compensation to software developers.And that is the second advantage of computer viruses.Maybe computer viruses could be of any use here too.And be aware that computer viruses came for a long time, unless forever.Sometimes, however, creating viruses can become a respectable occupation, bringing constant income.What is a computer virus?They have to fight for survival in complex conditions of conflicting computer systems.Thus, let's consider creators of viruses as the best source.