I am not worried about Amazon despite some publishers and writers decrying their policies. Despite Amazon's seemingly bullying tactics towards suppliers, and their seemingly monopolistic position, they have not raised prices. Their low prices benefit the consumers. They get a better deal for customers.
In future, if they were to try to raise prices after crushing all opposition, they will only open themselves to new players to come in with better prices. I am not worried about Amazon.
With regards to writers claiming that they are affected, yes, they need to negotiate a better deal with the publishers, that is between them and their publishers, not the bookseller like Amazon.
Yes, I am buying truckloads from Amazon these days since brick and mortar booksellers do not meet my needs with their limited selection nor their prices.