If sales are an indication of quality:

The best hamburger in the world is the Big Mac, beating In ‘n’ Out, Fudruckers, and your favorite burger.

Spider-Man 2 is the best movie ever made, beating Citizen Kane, Seven Samurai, and your favorite movie.

Harry Potter and the Sorcerer’s Stone is the best fantasy novel ever written, beating out Narnia, Lord of the Rings, and your favorite fantasy novel.

Stephen King is the world’s best writer, beating out… well, everybody.

You can see where this is going.

* * *

Sales figures are important. They indicate to us what percentage of the
market is interested in the product. But quantity of sales is not a
direct indicator of the quality of the content. Marketing, production, presentation, branding, etc. are all important to analyze.

Sometimes, they’re more important than the content.

Sometimes, the content doesn’t matter at all. It’s all in the marketing. (See: Jerry Bruckheimer)