One question bothers me a long time and I am not sure if there is anyone that thinks about this before. Let's say you invested $10K in Bitcoin when the price was $20K,  and some time later the price pumped to $40K, which means the initial capital is now worth $20K. For some reason, you need cash urgently so you decide to sell the Bitcoin you own for cash. You do it and now you have that $20K on hand.

In this process of trading, your profit is $10K for sure, regardless of whether the Bitcoin price will pump or dump. If you won't invest again, this beautiful success should be what you are proud of. However, 99% of us will choose to buy again and hope for the next success. However, now you buy at $40K and the price may drop to a new low below $20K later, and the profit you gained from last trading may be eaten up gradually by the market dump.

Connect the two dots(two extreme conditions) and draw a curve, high chances are that at last, your profits from all investments may not be that much, at least much less than what you expected when you first gained that $10K. Therefore, all the occasional profits between investments may become fixed or variable costs that these investment must pay.

Does this sound logical to you ? What do you think of all the interval losses from the investment gains ? Please let me know.