If the product is not manufactured by yourself Amazon will cut you out entirely as that is their business model. You have to manufacture yourself or own the brand or rights to the brand in order to have a future with Amazon.
I guess it is not the case in Indian business. Reselling is something that is allowed by Amazon. I see a lot of videos where people say they buy stuff in the market in bulk and sell them for a better price online.
Yes I am sure that is happening, but long term they do get muscled out and that is how Amazon grows as they become supplier and seller making all the profit. This has happened in every country thus far.