Something being popular does not, in any meaningful way, communicate that it is a superior product, neither in design, nor in execution, nor in materials. Popularity tells you that, in the context where the product was deployed, it was seen as a desirable purchase. Higher quality products are not at all guaranteed to be the bestseller, not even guaranteed to be in any particular position. Indeed, the bestseller is usually the cheapest product that doesn't fail too often nor too severely. Even that last one, severity, is up for debate if the catastrophic failures are rare enough. Consider the Pinto, very popular until the whole exploding gas tank case came along.
A thing may sell, it may in fact sell extremely well, and still be a mediocre product. A thing may have very low sales, may barely sell at all, and still be an excellent product. Popularity does not meaningfully sort for quality. Note that this goes both ways; I'm not inverting the fallacy either and saying that popularity indicates something is a bad product. I'm saying that there is no relationship, not even correlation, between sales volume and quality. If there were, we'd see a lot fewer crappy, crappy blockbuster video games that somehow still made bank.
In specific, this reasoning is a form of argumentum ad populum, a subtype of appeal to authority. It would be a fallacy to assert that this means popular things are bad or wrong. Instead, popular things are...popular. There may be many reasons why they are popular/sell well, with quality being just one, and frequently quality is not the most important concern. If we wish to make assertions about the quality of a sold good, we must ground them in the actual...you know...qualities of that good. For physical objects, the materials from which they are made, aka the "production value." For most things, the design and utility (since most products have SOME kind of utility value, even if minimal). Ease of use, interoperability, elegance, etc. Sales don't tell you anything about these things.