With So Many Startups, Where Does One Get Customers?

There are more than 1B people online.

divide that by the number of websites wanting attention

.. And if 1% of China bought my product.. !

I can arbitrarily, yet confidently, state that 70% of all websites are garbage and are not being maintained.

Secondly you are not directly competing with the remaining websites. People do not spend all their time online. If you convince them to use your product, it is not as if they will take time away from HN to read your blog. They will simply take that time away from their offline activities or hours of boredom.

By finding a niche market and attacking.

the best services usually attract the customers.

don't be a bottom feeder.

If it's easy, everyone will be doing it.