Bitcoin is and always will be very volatile, but this does not mean having to give up his purchase. If you look at the chart of growth rates you will see that every year the price of bitcoin is increasing. This trend will persist for a very long time so you can buy it at any time.
so i should buy bitcoin at this point or when the value reduce.
You could wait but there is not guarantee the price is going to get any cheaper in fact the opposite may happen and bitcoin may become extremely expensive so at the end of the day you are the one that needs to take the decision of whether or not you want to buy bitcoin at the current prices.