Selling is tougher than buying?

After investing for some years in stock, disregard whether we are technical or fundamental followers, I believe most of us have developed our own "style' in buying and selling.


I personally find buying is always an easier decision as long as it appears undervalued (after my own analysis) to me and it is a good company with business that I can understand. When I make the buy decision, obviously I expect to make profit from it though I am also prepared for further fall in price and make it even cheaper, but to me, what trigger the buy decision is always easier - undervalued.


However, I face more challenges when come to sell decision - especially selling at a profit versus selling at a loss. To me selling at a loss are usually due to some major changes affecting the fundamental of the company or it has reported a results that I did not expect and totally unexplainable. Though I have worked out the indicative intrinsic value in most cases when I buy a stock, I am still not as decisive in selling a profit making stock as compared to buying decision or selling a loss making stock. The only time this is easier for me is when I find another undervalued stock which is more attractive and I need the fund. Seriously, the fear of selling too early and make less profit or miss out another multi bagger is more scary than selling at loss...am I insane?
I tried to review what is "disturbing" my own thought process:-
1.  Could I be wrong in my Intrinsic value (IV) calculation - as working out IV involves many variables (discount rate, future cash flow, growth rate)  based on assumptions, the numbers can be in a wide range?
2.  What about PE- can Mr Market gives a higher PE to the company now as the overall market is trading at much higher PE?
3.  Are there some development in the company that I may not be aware of but insiders quietly snapping up the share?
4.  Technical analysts telling you that the momentum is strong and it is buy signal and I am acting like a fool?
5. My investment horizon is always longer term, why worry - good company share price should continue to climb even though there are fluctuations every now and then, this could potentially be my multi bagger stock


But then on other side, the little voice tells me a bird in hand is better than two in the bush. I heard from a successful investor once said - you will never be wrong to lock in profit!
We only know whether we have sold too early when we look back later, but at the point of making the decision, it is always right basing on our own guiding principles. Otherwise, we will have inconsistent decision from time to time and our learning pattern is unstructured and make it harder for us to improve and be confident on this stock investment journey. Having said that, I usually review each decision if I have missed out any sign or is there something I can learn from it if the decision appears a painful one, whether a profit or a loss. Of course, no 2 cases are exactly the same! Yes, I am still trying to improve on this swing so that I can hit it at a better spot! Happy hunting and harvesting!