But, Most of the people talk only about top 10 or 20 hosting.
Why not rest?
Think of it in terms of music. If you're not in the top 20, most people will soon stop mentioning your song, and eventually might even forget it was popular at one time.
That being said, the top 10-20 hosts pay a lot on advertising, compared to the others, both for proper ads, and by paying affiliates for sales they bring in. Many of the smaller, but otherwise quite good hosts, don't advertise at all. They're happy with the free referrals they get from their current customers.