KitaYama, your post is an excellent presentation of an important fact. Getting a pet involves bringing a living being into your family... a living being who will (hopefully) adapt to become a reasonably-behaved member of that family, a being who can accept and return some level of affection. (Some children take longer to adapt than some pets.)
When you adopt that creature that cannot obtain its own health care and proper food, you take on responsibility, not QUITE at the level of a new baby, but a big responsibility nonetheless. You also face the issue that at some time in the future you might face a difficult decision, one that will tear your heart out. The animal may reach a state of debilitation so severe that you have to consider the mercy of euthanasia. In civilized countries we do not put out old pets to die on their own. But if they don't die on their own in your home, what will you do?
My step-daughter has had to make this difficult decision for several pets, at least two cats and a dog, at different times in her life. She is now in her 50s and has had pets for at least 40 of those years. Each time, it tore her apart emotionally for several days. But she is a "pet" person and has at least three pets shared with her partner, whom she is marrying next week.
The decision belongs squarely on the pet owner who chose to give a comfortable life to that animal and chose to love it. When you accept responsibility for that pet, you must eventually consider the suffering of an animal that is slowly reaching the end of its normal life span.
You gave it a comfortable life that it couldn't have obtained for itself. Will you give it a comfortable and peaceful death? Can you? I'm not saying you should do anything, KitaYama - but your "mountain" that you mentioned includes the fact that at some point you have to come down off the mountain and into a valley. All things - good OR bad - must eventually come to an end. The question is whether the end will come with dignity and a final show of love for the animal.
It was four rooms all in a row, kitchen, living room then bed1 and bed2 on the left with a hall to close them off and the bathroom straight ahead. The two cats would start in the dining area and race across the living room and down the hall, they would take a banking turn on the hall wall outside of bed2, fly across the bed, up the wall in the far corner and reverse out, banking again outside bed2 and then up the wall in the dining room. We had carpet so they weren't sliding around like your video and they had such a good time that I never tried to stop it. Then one night we were visiting our downstairs neighbors when the cats wound themselves up. They sounded like a herd of elephants. Good thing the girls said they didn't mind because by that time, the game was well established. At least they didn't do it at night.
