There is nothing wrong with the model PG puts forward, as a start, but it is a simple model and it needs explanation. At the least, you should make some attempt

There is nothing wrong with the model PG puts forward, as a start, but it is a simple model and it needs explanation. At the least, you should make some attempt to explain why things change over time. Consider radio in the USA, up until the mid 1950s. It was eventually replaced by TV, but in the 30s, 40s and 50s it was the main medium of mass communication. The nation lived by its radio. The potential audience for a radio star was greater then than it is now. So why do top stars, like Rush Limbaugh and Howard Stern earn such large fees now, when the market is so fragmented? Changes in the tax code are important to consider. As a thought experiment, imagine if the top income tax rate was still 91%. (During the 30s, 40s, 50s and early 60s, it was 91% on income over $100,000, about a $1 million in today's money.) How many stars would ask for income in excess of $1 million if they knew it would be taxed at 91%? They would probably instead ask for various perks, which was the trend in the US during the mid-20th century. Asking for perks instead of cash remains the trend in those nations with strongly progressive tax rates, for instance, Sweden.