if someone sends you this message FIRST they are very bad at messaging. they may be bad at messaging but in real life they're kind-hearted.
Rather, if you send a message, first, and they reply with "hi" it means that the person doesn't want to be rude by not replying but doesn't, really, want to be messaging you !
Karen - "hi"
Toby - "oh, i bet you're a really lovely person in real life !"
Hi is wat u would type when u r trying to get rid of some videos that ur parents would not like u too be on. It is a rush so u type the shortest word u can think of to make u look like an innocent little bitch.
"Oh no I have to make myself look as innocent as possible I must type "hi""
(Hello) ( g'day ) (hola )(bonjour) (こんにちは) and many others
こんにちは私はピザが好きです hello/hi I like pizza