... as I randomly read in an online post.
I beg to disagree.
I don't know. I just felt like it did not sound right to me, so I made this note (LOL).
I think unhappiness is caused by yourself. Your own fucking self. Happiness can either be simplified or distorted in a million ways, and it's up to you how to view every single piece you encounter. Given the diverse people and circumstances you get a hold of everyday, I think you're bound to see them and consequently, end up with a comparison. As you observe, you get to differentiate. Whenever you compare, you see how things are alike and how they differ. If you take things positively, then comparison would not make you unhappy.
I suppose comparison is nice in its own way. Personally, it poses a challenge for me to see how things actually are, and if I end up wanting to have the same (or a better version of it) in my life, then the game is on. I enjoy good, healthy competition. It's a matter of your own POV. Having it on a positive note, comparisons can lead you to making the right choices. How do you think you're able to weigh your choices if you don't compare?
Nothing's wrong if you end up comparing what's out there. If you take it as a constructive boost in any way, then that would cause you some good. Be your own version of a happy, incomparable soul.