We all want what other people have. It's been proven in experiments that a person can stand on a cerbside and offer freestuff. People just walk past. Put a crowd around that same person and folks will flock to his side.
A guy chats you up and you think 'yeah, ok but not interested'. Put a hot woman by his side after you've turned him down, and suddenly you're thinking he's a lot hotter and you wonder what you passed up! Of course this works both ways for the guys that are reading this !
It seems my four beloved paws have a similar outlook. The three rescues I have were all quite happy with their dogbeds until I got the fourth lost pooch who has now joined the Mutley Crew. She's a lot smaller, 8 month golden spaniel (now named Goose) so when I got her a dog bed it was half the size of the others.
What happened? All three other heffalumps have been determined to squeeze themselves into this dog bed, entirely ignoring their own. They look ridiculously cute jammed in there ... but still, it just goes to show that we all want what someone else has ... even if you're a dog.