When your favourite show gets cancelled, it can be soul destroying. When it goes out on top with a great ending, it feels like TV time well spent. When it sticks around too long and disgraces itself over and over again, it's just plain infuriating.
If there's one thing the world's biggest shows nearly always have in common, it's a top notch Season 1. The first instalment sets the stage for the rest of the show, mounting a high bar fans will come back to see exceeded next year. While fandoms sprout like weeds, sharks start getting jumped.
Budgetary restraints, cast members leaving too soon, new (worse) writers taking over. Any number of reasons can prompt a series to slide off a cliff. Before you know it, the once praised show becomes a joke, even the good stuff is dismissed and history treats it appallingly (or forgets it completely).
You get millions of cranky viewers realising they spent literal days of their lives watching a show they now hate, wishing they could go back and do something else with all that lost time.