My friends an i were playing carcassonne and one of my friends was fairly behind, while myself and my other friend were potentially very close in points. My friend in last place decided to place a tile that very clearly let my other friend have a MUCH MUCH higher chance at winning and myself a lower chance at winning. My friend who placed the piece did not benefit or lose anything from this. I was very upset by this because i thought it was bad board game "manners". He essentially "chose" who would be winning the game with that tile placement. This move did not directly effect me in anyway but it let my other friend gain a massive advantage.

After doing some reading i realized that this is technically not bad etiquette. Do you think that if you are losing you are allow to "decide" or change the outcome of who wins just because you are losing and perhaps a player earlier in the game did not make a move that benefited you so you chose to have them not win?

I personally feel like you should not help other players unless it also helps yourself. You should always be trying to get "ahead" whether thats trying to get into 2nd place from 3rd by sabotaging the 2nd place player or by doing a move that benefits you in some way.

What are your thoughts?

(This nearly caused a huge argument because i left the game. However, we did finish the game because tabletop simulator autosaves. I realized leaving is also bad etiquette but i was quite frustrated. I think all ended well.)