Re: Why investors invest in bitcoin though some of them loose it ?
We never know what the future market looks like. If you do not know what to do. Your failure to fluctuate markets and you are ready to act quickly so that plans not only cover the results you expect to happen. You also need to have a specific plan for the worst situation not to recur. 
The least thing that I am seeing that is why they are losing part of their bitcoin is that they don't value it much, they are just after the income but they are not considering that bitcoin was most of the time also dumping, when bitcoin dumps they were panic and creating noise in the crowd.