I've played tabletop roleplaying games for a few decades. I've gamed with others who have no sense of character concept. They read the rules and think of ways to exploit them instead of having their character make sense.
For instance in Rolemaster, players can develop skills. Doing so usually determines the player's chance of success in a skill, except Ambush. Ranks in Ambush alter damage rolls favorably in surprise situations.
Rolemaster allows bonus ranks to skills, called "hobbies." Sure enough, some players will add free ranks to Ambush. How do they justify this? "I hide and surprise people for fun."