You’re spot on, GMZ!
Amazon is winning because its business model, which as you noted couples convenience with availability, is simply a winning model.
Not only is that model great for consumers, but it’s also nice for the planet (people don’t have to drive around town looking for products) and it has provided a platform upon which millions of sellers have been able to build their own profitable businesses.
Like all human-run enterprises, Amazon has its problems, but all-in-all Amazon is good on many levels.
And until somebody comes up with something better, Amazon will continue to be my GO TO resource for buying the things I need for my business and personal use.