Masturbation extreme, 3-4 times a day, can it cause problem in the long run?

Yes...: Apparently, you have a lot of energy. Good for young. But i like to congratulate you for knowing of being "extreme". If you can better use your energy for something else other than masturbation alone, you will have much brighter future. Remember overindulgence and obsession are the most common chronic killers of life, but least mentioned for not invading privacy so to serve political correctness.