Vincer

A person who hardcore grinds a game for a couple of days and then switches to grind another random game.

Usually, this person tries to persuade his friends to also buy the game just to quit the game as soon as their friends buy it.

Guy 1: Want to play Game X? I just bought it.
Guy 2: No, I play Game Y. It's incredible, you really should buy it.

Guy 2 is a Vincer