well, i think that reasoning is fair if you're talking about humans, because nobody really "deserves" any specific person, and the same goes for animals. nobody should feel entitled to a living, breathing thing, and nobody should expect or force anybody to be with/around them just because they think they "deserve" it. and it's true that thinking something like, "well, i deserve a mansion! and fancy cars!" and then getting upset because you never get those things is foolish. but the things you actually
need? i don't think there's anything wrong with saying you deserve them.
i believe that people do deserve happiness. it's a decision you make every day, to just let yourself enjoy things and feel good about life, even when things are bad. people deserve to have that and keep it, and so do i. i should be able to just. let myself be happy, instead of squashing it every time the feeling surfaces because i'm afraid it will get taken away. or worse, feeling bad about being happy because someone else tried to make me feel bad about myself, or feel guilty for having fun.
but saying people deserve good things isn't necessarily
promising those good things to people, it's just saying they should be able to have them. it's saying it's OKAY for them to have them, and to not feel guilty for wanting them or enjoying them.
but maybe you mean people misunderstand the wording and expect someone else to
give them happiness? or that they think other people owe them happiness. i understand that that's not how it works. you'll never be happy if you live for other people, and in the past i've found this out the hard way. if you only rely on other people to make you happy, you also give them the power to take it away. and that leads to bitterness, suddenly it's
their fault you're unhappy.
...but even though i say all of this, it's true that just because i understand it doesn't mean i don't still struggle with it. xD i'm working on it.