Luck is also part of the equation, perhaps more than people want to acknowledge.
To take Hacker News as an example, there are many excellent projects posted in the 'Show HN' section that get no traction at all. And then there a few lucky ones that suddenly take-off. There's no "wisdom of the crowds" moment that propels one project to success over another because it's more worthy or excellent - it really is random in so many cases.
We think success = product excellence: how else could a product rise to a leading position in the market or to such pre-eminence unless it was better than the alternatives? But the mountain of successful products ranging from mediocre to terrible quality shows that product excellence isn't always the key ingredient to a product's success.
Lest this all sounds too negative, I would never discourage anyone to pursue their product idea. But when it comes to promoting a product, developers should be cautious about relying on just one source for promoting their product (Hacker News, Product Hunt etc).