It is not necessary to have personal experience in certain things to understand whether they are good or bad. Here is a an analogy for you to understand this situation. A shoal of fishes come across an obstruction in the water with an unusually small opening. It is actually a trap laid by a fisherman to catch the fish.
Some fish want to go inside the fence and see what it is, but the more experienced fish advise them not to do so because it must be a dangerous trap. The young fish asks, 'How do we know whether it is dangerous or not? We must go in and see, only then can we understand what it is.' So some of them go in and get caught in the trap.
We must be prepared to accept the advice given by wise men like the Buddha who is enlightened. Of course the Buddha himself has said that we must not accept his teachings blindly. At the same time we can listen to some wise ones or other religious teachers. This is simply because their experience is more advanced than our limited knowledge regarding our worldly lives.
Parents usually advise their children to do certain things and not others. By neglecting the advice given by the elders, young people do many things according to their own way of thinking. Eventually when they get into trouble, they remember the elders and religious teachers and seek their help and sometimes even ask the religious teachers to pray for them.
Only then do they remember religion and seek some blessing and guidance. But they do not think the main purpose of a religion is to help us to follow certain noble principles to avoid many of our problems before they confront us. Early religious education trains the mind to cultivate the universal principles which support our way of life to live peacefully.