Yeah I think this is one of the most common mistakes when it comes to trading. I've had several of these as well though fortunately the amount that I lost is only minimal. It's really important to make sure first the amount you're going to be selling it and to make sure you enter it correctly.

Wow it was a grave mistake I think. Supposed if you just want to try is better in minimal amounts and did not much like that, because it would be too risky for loss. I've also ever do the same as you, but not much like that because I only spend the amount to much like that was for coin that really can a profitable. Maybe my suggestion to be more careful again and make it a lesson, friend

That is too much losses. My mistake sometimes is that I set order and forgot it. When my BUY ORDER is filled, and check it next day the coins price is  very low or being dump already and its hard to recover. It is better to active and updated always when you trade. 

Indeed, most of the gamblers became greedy, for hoping that they will become rich instantly, until they didn't notice their character became addicted to the games in gambling. which leads them to loss of big amount of money.

One simple rule to avoid loss in trading which is in your hand is : -

If you buy btc and see price is rising you tend to hold btc in view of price to rise further and suddenly price slump and you end up with less profit or wait for another price rise. Always have target if it reaches that level you will sell it.

My biggest mistake is chasing my loss, when Synereo price stated dropping immediately after their ICO, I thought this insane, how could token sold at 33ksat be price 26ksat so I started buying the more as the price dump. It was a dump decision, I will never made again.

This is one of the most common mistakes that novice traders do

But sometimes even experienced traders fall for that error too. This is aptly called "catching falling knives". Such traders instead of closing their losing positions and cutting their losses short start adding to them thinking the price will soon revert and they will offset the losses. Sometimes it does actually revert, but ultimately such an approach leads to heavy losses in the end because these traders start believing that they know better how the price should behave, and the market eventually punishes them badly and wildly

i think mistake in trading is a very common think everyone much have the experience of making mistake in trading. because no one can be perfect. for example in previous days when the price of bitcoin reached to 1150 USD i  made a big mistake  that i still hold my bitcoin and not sell it, because the price of bitcoin after that comes down to 740 USD round about.

Yes, I was do the same thing. I just guess that it's the time to get profit, without make any analysis about it. But that is normal the first stage of trader is being unconscious incompetence, I am sure that I will go to the next level of trader.

I was assuming it is the price manipulation by the whale. every time the whale can dump his coin to make everyone aware if the dumping session was happening and they will be doing the panic selling and sell his coin for cheap price and the whale will pump it again.