Though domain renewal fees exceed the online advertising revenues, the domain investor is still spending money, only because it is a fairly passive source of income. For a person who does not have a salary, there are many times when she cannot sit in front of a computer and do writing work.
When a family member is not well, or she has some health problem, making it difficult to do computer work, the writing income will reduce to zero
However, she will have some advertising revenues, even without working since the advertisers are paying monthly