I search a monster MC who stay true to what he is, he kill human and monster alike, prioritize his own life above everything else, doesn't befriend other apart for killing them or reap good benefit.


I don't care about the race of the MC ( he can even be human but with the mind of a monster)

Best example of your description would be ELLC:
https://royalroadl.com/fiction/8894/everybody-loves-large-chests - monstrous box who only cares about its shinies, ongoing
Others:
https://royalroadl.com/fiction/12712/parasites-and-magic - insect queen thing(?) that lacks any form of sympathy for humans (you'll see), ongoing
https://royalroadl.com/fiction/7578/demons-journey - overall ruthless demon protag, completed
https://royalroadl.com/fiction/2813/the-damned - similar to demons journey, hiatus

I'm sure their are plenty more, but these are those that come to mind with your description. Try using advanced search if you want more stories.

I'm sure you'll like this one

https://royalroadl.com/fiction/3977/the-child-of-ebon