https://www.bloomberg.com/news/articles/2014-03-03/advertisi...

TLDR;: But in one sense, the advertising business is about as static and boring as they come. The industry has never grown in scale. Looking at data since the 1920s, the U.S. advertising industry has always been about 1 percent of U.S. GDP. It’s surprisingly consistent, mostly tracking between 1 percent and 1.4 percent—and averaging 1.29 percent.

So when you said, "...eating from the same pie", according to the linked article, they actually are.