Funny enough, almost every seller on Amazon buy’s wholesale, hopefully all are selling for a profit.
I can see your biggest obstacle right now is trying to find inventory. You might not be able to get much help because of how the 80/20 of a marketplace based ecommerce business works.
It’s best to see amazon as a marketing partner. You don’t have an “amazon” business, but rather a business that sells on amazon. You leverage amazon’s enormous user database and marketing campaigns as a way to sell your items. And in turn, you pay amazon a fee for their service.
However, Amazon is available to anyone to sell on. Making the barrier to entry very low. Since the barrier to entry is low competition is high on the selling side. This means you will need to master the sourcing side to be successful. Mastering sourcing means taking advantage of market inefficiencies, sourcing low barrier to entry products (generic chinese wholesale) at a large volume to play on price, creating exclusive selling agreements with companies/fostering good relationships with large companies so you can get more exclusive products etc.
You also need to create your business model to suit your needs. This could mean selling items with a high volume at a lower margin, or selling higher priced less desireable items at a high margin. This will greatly change the way you source items.
I highly recommend learning more about sourcing and ecommerce in general while you build your store. You can very quickly lose a lot of money if you blindly go into this. There are a lot of great free resources on the web, youtube, and books on the subject which will help you get started.
To the outside many people don’t understand this business is a grind, just as much as any other business. Supply and demand will always regulate any market with enough time, and Amazon is mainstream enough at this point where the supply of sellers makes the available demand of purchases competitive. Be the smartest, craftiest, and take risks and you will survive.