You build it once and it keeps working for you. Whether it's a PDF ebook, course, or software; it scales. You may update it every once in a while but the bulk of the work stops after the upfront investment.
Now, the good thing about services is it allows you to earn something substantial fast. Say, someone reaches out to you because they trust your internet marketing skills, it's easy to find a setup that works and earn significantly. You just have to be flexible enough to serve the demand.
But services come with the downside of lack of scalability. It's somehow in between of getting a job or selling your own products.
In the long run, I argue that Products is definitely the way to go, but the challenge is gaining enough traction for full time income. For most people running self-funded businesses, it may take too long before the products you make are enough to replace what you'd earn from a job.
For those looking to earn full time income, would you suggest:
1. Going straight to selling products
2. OR begin by selling services first