Mass-publishing markets are very strongly given to power-law distributions. We hear that "anybody can be famous" (or successful, or ...), but everybody cannot be famous. Attention and publicity are the ultimate zero-sum games: no matter how large a given talent pool, there will only ever be ten top-ten spots, 100 top-100 spots. All you're doing by enlarging the pool is amplifying the competition for those spots.

There's another side to the equation, though, which is the scope of the audience. Prior to modern technological methods, and I'm including here everything from relatively modern printing (say, 19th century onward), as well as phonograph, cinema, radio, television, and sound amplification, the reach of any given work was small. A book might have a printing of several thousand copies (Adam Smith, Wealth of Nations, ~5,000 initial print run, and the cost at ￡5 was roughly a quarter of a working man's annual wage). A theatre might seat (or stand) a few thousand (the New Globe Theatre: 3,000), and the largest cities had populations of about a quarter million (London in 1600, more or less). Transportation was slow and expensive (Smith again: 2 weeks, by stage coach or horse from Edinborough to London -- that's how he travelled to university himself).

https://www.oldbaileyonline.org/static/Population-history-of...

As a consequence, entertainment was strongly local. There might be small touring acts, local musicians, and in rare cases, artists with a noble or royal patron (think Shakespeare himself, after a fashion, or Handel, Bach, or a church appointment (Bach, Telemann, and others). Art as a freestanding business was more-or-less a 19th century creation -- look especially at the Pre-Raphaelite Brotherhood and the Impressionists, there are several excellent documentaries and biographies of each.

Technology increased the reach (and income) of top performing creators and stars, but decreased the viability of those further down the rankings. Where it used to be possible to eke out a livelihood as a local or touring performer, this became far more difficult. (There's something of a reverse shift in that the overall entertainment budget has increased sufficiently that the field has expanded, but the overall balance holds true.)

By way of quantification, I've been looking at the question of how many actors there are, and how many of those are considered "A-list". For the first:

How Many Actors are in L.A.?

https://hollywoodsapien.com/2012/07/05/how-many-actors-are-i...

Based on SAG and AFTRA membership and some adjustments, anthropologist Scott Frank comes up with the figure 108,640, of whom 21,728 are working actors. Los Angeles itself provides about 80% of all acting work, and USBLS data claim 1.77% of Angelenos work in entertainment, more than any other U.S. city.

How many of those are considered "A-List" actors? The definitions are ... fluid ... but generally about ten, no more than twenty. The Ulmer scale is a 100-point model estimating a star's value to a film. The 2009 top ten list, in order, were: Will Smith, Johnny Depp, Brad Pitt, Tom Hanks, George Clooney, Will Ferrel, Reese Witherspoon, Nicolas Cage, Leonardo DiCaprio, and Russell Crowe.

https://www.webcitation.org/5mnRWTArh?url=http://www.ulmersc...

Consider that given power law relationships, the earnings of a given star are going to be 1/n of the first-ranked, income falls off tremendously quickly. VSauce has a surprisingly good video on the topic:

https://www.youtube.com/watch?v=fCn8zs912OE

Upshot: We're not all going to fame our way to wealth and riches. Or even subsistence survival. It's not a creators world.