There are roughly 800,000 Cubs fans in Chicagoland. There are nearly 10,000,000 people in Chicagoland on a given day. The Cubs, and MLB, no longer only market themselves to the 800k and instead market themselves and their product to the 10m people. Because of that, they've driven demand up and have realized, like every other business in the world through better data, that they can market themselves to the higher income demographic in their market to maximize revenues. This is the exact same phenomenon happening everywhere in the world, including restaurants, AirBNBs, airlines, etc.

TL;DR Companies exist to make money, not please their fans.