Maybe they don't want to risk their lives? Kirito estimates that around 2000 of the remaining 6000 players are still in the starting city and don't venture out because they don't want to die.
They still need food, because while it is irrelevant to their bodies' condition, they still have the urge to eat. They also need somewhere to sleep where they won't get murdered. This all costs money, and somebody has to go earn it.
Kids might be great at video games, but I don't think I've seen kids play under threat of death. Realistic looking monsters trying to eat you would only make it more terrifying.

The best way to ensure that you live is to not leave the starting city at all and wait to be rescued, either by people outside the game or those clearing it.

The fact that you guys say your suspension of disbelief is blown away because there are 10 kids who don't want to die and someone willing to look after them just boggles my mind. You don't even need to suspend disbelief to accept this scenario, just common sense.