That is a very good advice. Online earnings cannot really be predicted. Websites come and go and technology keeps changing. So it is best to have offline ventures and not rely on online work alone. It can just be an extra source of income.This is one of the question that I've been running through the mind of all online workers, we might not be able to give an accurate answer because we do not know what will happen in the future,i always advise people to start up an offline business and use the online business as a backup in case anything.