That depends. Like with any business in any category: Whether or not you will be profitable is mainly dependant on your skills.
The skills that will determine if you make or lose money or time doing affiliate marketing could be your search engine marketing skills, your general online marketing skills, your content writing skills, your level of persistence and commitment to become profitable, or your ability to hire the right people to help you achieve profitability.
I know for a fact though that affiliate marketing can be really profitable once you get up and running.
For me, it took years to start getting enough income from affiliate marketing to call it my full-time job.
See all questions and answers in my affiliate marketing FAQ