Abusive words

Human beings mainly operate on the basis of emotions.  While the intellectual (symbolic) mind knows it's just a game, part of our brains interprets chess as a life-and-death struggle.  People like the effects of adrenaline!  I try not to take rude comments personally.  If it's obnoxious, just mute the chat, and find another opponent.

Some more than others.

its something normal, many players when they alredy lose send me messages saying I am an idiot, but just ignore them and block them, its not big deal

that is why I prefer to disable chat

they're just salty

I'm on a low sodium diet.

Batgirl is correct that some humans are more emotion-based than others.  A natural result of evolution since diversity makes the species more resilient in the face of unexpected catastrophes.  Of course emotions have an important role, so we need a balance between intellect and emotions.  If we understand this, then we should not be surprised when individuals misbehave (are "too salty"), and so their's no need to be offended by the natural (although sub-optimal) display of human nature.  Just fight on the chess board, or flee to another opponent.

some people are very rude . I like to chat with my opponent when I play online chess but sometimes they don't respond.

Sodium is essential for the body, especially the nervous system. You need it to fuel the sodium-potassium pump in nerve cells for the action potentials of neurons firing to be strong enough.

I have been doing ketogencis for 1 year, as of today.  Salt is very important on this way of eating.  I use pink himalayan salt.

While sodium is important to the body, according the American Heart Assoc., 90% of Americans consume an unhealthy amount of salt daily and most of this comes from restaurants and packaged foods- so much so, that maintaining a proper level takes some effort even if you don't own a salt shaker.  Besides high blood pressure, excessive daily salt intake can put you at risk for heart failure, kidney disease and osteoporosis among other things.  Of course, one can say this is baloney (which contains a lot or salt) but I prefer to rely on accepted science.

There are a lot of dorks who don't do well socially and put all of their value in chess. These folks flip out when their one saving grace lets them down.  I suggest disabling chat when the game begins if this is much of a problem.