Mom tells 23-year-old daughter that she's the only one of her 7 kids who is a responsible adult, 25-year-old daughter overhears and freaks out: 'I don’t rub my success in my siblings' faces.'

The most responsible daughter didn't explicitly agree with her mom, but she didn't disagree with her either. 

It can take many years for young adults to become responsible and independent. It all depends on how they were raised, their socioeconomic background, and how eager they were to leave the nest. A small minority of young people are fully prepared to be independent of their parents the second they turn 18, but that group is nowhere near the majority of 18-year-olds. Many 18-year-olds are still in high school and rely on their parents for housing and food. It shouldn't be expected of an 18-year-old to fully support themselves in every regard. You should only be concerned if your 18+ child is a NEET: Not in education, employment, or training. If an adult isn't in school or working full-time for a prolonged period, it could be a sign they'll struggle to be a productive member of society down the road. If they have a genuine reason for not being able to work, that's one thing, but being lazy isn't a good enough reason.