So you enjoy wasting your time on a show you know has been cancelled and has no "ending"? Ok...
It depends on the show. Some shows don't have an ending. They may work up a goodbye episode, but they are not long arc epic stories - they are a series of short stories. They can be fun to watch even if they are going away. (And who knows, they could be revived in a future season or by another network.)
That's like starting a relationship with a woman you know is leaving town forever next week. Total waste of time when you could be dating someone that isn't leaving town for good.
Better to have loved and lost than never to have loved at all.
Perhaps a relationship with you is just what that woman wanted ... and she will cancel her plans to leave town if only someone, anyone, possibly you, would give her a reason. You never know until you try. But I suppose it is your story ... so your rebuttal will be to add more fiction to the hypothetical - reasons she can't stay. But following your policy of not paying attention to stories that won't last we must ignore your story of a woman leaving town forever, as we know your story will die when this thread fades into the ether.
Shows are kept based on viewership. Your refusal to watch shows on the fear that they will be canceled reduces viewership. Perhaps you should be giving a big thank you to those who take the risk - who watch the shows while they are in their premier seasons - who make the shows popular enough to have them renewed. Without those viewers you wouldn't have shows to binge watch once they are renewed. You should thank those viewers.
Those that took a chance have convinced your potential lover to stay in town. You owe them gratitude, not scorn.