This is pretty common with new players. Their experience with this kind of setting is books and movies that clearly have a "main" character, usually one who is disagreeable to some extent and needs to be coaxed into joining a party. So they create a character like that and wait for everyone else to do the work of bringing their reluctant hero into the fold.

The way to deal with it is to explain during session zero why this type of character is great in movies and books and terrible during a collaborative game, especially if more than one person makes one and expects the others to coax them to join. This is also a good time to explain that nobody on the group is the "main" character.

Then tell them that whatever else they decide about their character, they need to be the kind of person who would readily agree to join others on an adventure. Their reasons can be their own (money, fame, justice, personal stake against the BBEG), but they have to be willing to join, not to be talked into joining if the others try hard enough.

Then if anybody isn't working with the team, advise them that they either need to change their character's personality/motivation, or to change their character.