I would not says every time is being missed because to get the perfect timing is like either you exactly know that this situation will be happening or else it is just a coincided that you buy and prices drop or rise vice versa. Also many things are not in one's control so timing the buy/sell would I say may not be at all easy job.
So the question is do you always missed the right time for buying or selling your bitcoin? We know that we don't control but if you will have enough time to monitor the movement of bitcoins price. You can have the control on selling it and take the chance to get profit of doing both buying and selling. It just a matter of time and patience.
It is right, but i believe many trader missing a lot of chances but not always. Because in trading, we are confused, whenever we are selling our coins, because we think may be in the next time, coins will be increased more, and in this situation sometime we get lose. So you are right, we need patience and trading is time taking work.
Being patience is the key in being successful in any kind of field especially on trading bitcoins and while you are patient then try to study or read some news,articles or any kind of information that can help you to have a point of view whether you will sell it or continue hodling it for a bit longer.