Season 1s are great, setup, some payoff, a bit of lead into the overarching story. Then season 2 to X. The heroes win and then lose in the final episode, cliffhanger to next season. People get bored. Final season is announced and they wrap up the show.
Let me guess, it was about states rights?
To smoke weed every day? Hell yeah!
(But to actually anwser, it was about slaves and the profits they brought in.)