All companies work the same way – buying/building a product, marketing a product, and whatever "profits" you can produce can be used for life or reinvested in better products.
And although Amazon has been around for almost 10 years (anyone can register a product in their market), the fba profit analyzer at https://www.turbopiranha.com/profit-analyzer-for-fba-and-fbm/ has only just begun to become popular in the last 24 years.
If you did not go to business school to explain briefly how to run a business "successful", you need essentially to be able to provide a product/service to a wider audience. You want to aim generally about 30% net profit margin.
Now, just because the "digital" field is large does not mean it is devoid of how the "markets" generally work. Competition is a major force like the idea that because something is "easy", it can be reproduced relatively easily by others.
Image Source: Google
Amazon sales usually provide access to products that users do not have local access to or can access locally, but with major restrictions (eg color/size issues) or security supply problems. In other words, while the Amazon market is very large, don't think you can outsmart supply/demand.
The real trick with "digital" companies is to provide access to unique products that only you can access and you can check over here for more about amazon product orders. These products must focus on providing solutions that are unknown to most people, and therefore make online purchase offers legal.
Try to improve the set of skills that can be made available to a wider audience and which can be used to identify "products" that can be made and offered to simplify/solve the problems you experience.