For the entertainment. I wanted to pick a past-favorite game of mine, Magic: The Gathering (MTG). But then I thought, that game is rather expensive, maybe I should pick up poker instead, since there's at least the potential to earn money, and I can always play in a way where I can't lose too much. I love the strategic depth of MTG, reasoning about optimal play under uncertainty about outcomes. Poker has a lot of the same elements. In fact, a lot of the top MTG pros earn money on the side playing poker.
Second, I study game theory in real life, so I feel like I am almost obliged to become good at poker. Card games for money have been the focus of my field since its advent. The book credited with starting game theory, "The Theory of Games and Economic Behavior" by the brilliant John von Neumann and Oskar Morgenstern, has a whole section devoted to poker and
bluffing. The famous John Nash studied a simplified
poker game in his thesis. And Harold Kuhn introduced the famous game Kuhn poker as one of the earliest fully analyzed games.
I'm sure everyone was dying for a little history lesson in game theory

Actually I'm curious, how known are these historical game theory facts to the poker community at large? I know that people are at least aware of Nash equilibria, but does it extend much beyond that?
Edit: To put it in terms of your letters: A. And hopefully C some day in the future. I'm just starting out, after all.