He was born and brought up in this village, but after staying and studying abroad his childhood friends seem backwards to him; he _ this place now.
Or
He had lived in this city all his life but whenever he gets a chance he starts counting the flaws. He thanklessly _ his homeland.
It might even apply to a situation like say you party every weekend but if somebody else does the same you criticize them.
Note:
Read title: act of crticizing one's own homeland/city/country
I can use words like criticize, betray or badmouth in my sentences, but I am looking for more like an idiom or phrase or even a proverb, that may or may not fit into my sentences but explains the intent.
The intent here is being a hypocrite to an extent, yes but there's an addition of viewing one's own homeland or people as backwards(where I don't think that person has changed, they are just trying to show off).
In hindi there's a saying "jis thali me khaya usme ched kiya" which means destroying the plate in which you are served. I'm kinda looking for an english analog for this proverb. I thought "don't shit where you eat" would be the close but it was hilarious to find out it's meaning and of course that it's nowhere close.
Best Answer
You could call people like that "turncoats" or "renegades." You could describe them as "dissident."
No single verb I know quite captures what you've described, but try "abandon," "desert," "betray," "defect," or "dissent."
Words that fit into the blanks in your sentences are "resents," "scorns," "rejects," and "disdains."
When someone is different from their origins, especially when a child is different from his or her parents, people say, "The apple has fallen far from the tree." There are lots of variations on the phrase "too good for," and in this context someone might contemptuously say, "They think they're too good for us now." When people mock others for qualities they themselves exhibit, like the partier who looks down on other partiers for partying, you might say, "Look at the pot calling the kettle black."