Why do some people like to say ''Man'' at the end of every sentence?

[SBFNews]

"Yeah man"
''Let's go to the pub man''
"Gan Ni Na man"
"Fuck man"
"Cool man"

 

[UltimaOnline]

Same reason why Li Hongyi likes to say "like" as many times as he can when speaking, try keeping count in his video below :

 

[ThugSin]

They think they nigga but actually is chigga

 

[blackmondy]

I also dunno, man....