When you listen, you learn. How? Well, first, you won't know the tune to a ragam just by reading the name. You must listen to the song that the singer is singing. This way, when you learn a new song in that ragam, you'll be familiar with the ragam and might sing it even better. You can also interact with the singers and even ask questions afterwards.
First when you go, you might want to leave in half an hour. Try to pace yourself. On the 1st concert, stay for 1 hour. On the 2nd, stay for 1 and a half hours, and so on. This way, you will slowly stay for 3 hours.
As you can see, live concerts are important because when you listen, you learn.