Pets are weird. I once met a pet turtle whose owners described him as “a real asshole.” He was an unfriendly little murderer who offered nothing to be happy about. And that guy is projected to last another 40 years! That gives his owners two options: Let the next 40+ years of their life get stained by the ownership of a terrible turtle, or actively discard this one-time family member. At least when the same thing happens with people you probably didn’t have a choice in the matter.
That’s why the best pets are the ones that crap out after about 15 years. They last long enough to accompany you through maybe 2 or 3 significant lifetime milestones, which is a hell of a lot better than letting a little cruel monster define the majority of your time here on this earth. Sure, you might get sad if your loyal dog or favorite rat bites the big one, but it’s better than your pet outliving you and your children remembering you by inheriting your tiny spoiled asshole friend.
This is also why robot pets will never take off.