When People Express Their Cockyness

And I mean when you're a Jax top against a Vayne, and she just makes your life a living hell. And the worst part, she knows it as well. Did my best to endure that laning phase (if you could call it that), but to no avail, she just kept being relentless. Not just me, but her team is doing better than mine is. In those situation, the worst part for me is when the enemy team either spam emotes whenever we die from various things to various situations, or just express their joy in all chat. I hate it when people do that. Why can't they just not express anything that can demoralize you (though their may be exceptions idk). They know they're winning, and yet they can't be humble about it? I want to mute them, yet I can't bring myself to do that. Why do people love to do this...