Once I bought dart game for my son to play at home. It was bit expensive. As soon as we were at home we started playing. It broke within one hour. My wife was not happy and she said we wasted our money. I said loss did not happen now, it happened when we bought it. The time I paid for it, I had already discounted the value of dart game to zero but my wife felt loss only when it was broken. In this situation I was fine with it but my wife was not.
I am a conservative person I discount my losses well ahead or let’s say I provision for them immediately. I understand that same logic cannot be applied to all the things we buy for example we cannot bear or provide for loss of our real estate (home) investment, and big ticket items (jewellery, home furniture etc.).
For me loss happens at point of making payment. I feel that’s how we should assess our investments as well. You should do all the due diligence before making investments/payments. We should not feel loss is happening after the price of your investment dropped or when thing you bought broke. If you are able to sell your investment as soon as you realize your mistake you are only recouping your loss.
So for example, let’s assume stock you bought fell 20% from your buy price. You revisit the thesis of buying the stock and you find that you made a mistake. You should not think that your loss is 20%, you should assume your loss is currently 100% if you sell it you can recover 80% back. If you fail to follow this you are likely to have more losers in your portfolios, which will overall be drag on the portfolio.