In many jobs, your job becomes saturated after 5 to 7 years and you may not be able to get hike or increment or get promotion due to multiple reasons. While in digital marketing you can start as fresher and then grow as team lead, project manager, head of department and then Sr. Manager or you can also start your own business or can do freelance work. Your income grows with your experience and knowledg. (In other jobs, your income stays almost same even if your experience and knowledge increases)