Girls are definitely suitable for the office! It's easy, but it depends on personal experience and ability. In fact, it's not bad to be a salesman, that is, you can learn a lot by selling in the store. Maybe what you like is a good working atmosphere and a good relationship with colleagues. If you just want to find a good job and don't choose what you like, it doesn't matter how much money you earn.
With capital, you don't have to work, just open your own shop! You should take a long-term view when doing things.