A man is playing the saxophone in the street and some people are sitting on the curb next to the street by him.
A man is trying to earn money by playing for other people on the street.
In sentence 1 it doesn't state that he is trying to earn money it makes it sound like he is just entertaining.
We have no idea if the man is trying to earn money, they could just be playing for fun.
You can not infer he is trying to earn money.