As you can see in the chart most people got into the market in this rally, during which the aapl announced the apple pay, which people had already heard stuff before the launching day. So I guess the big rally was created by big players deliberately. They wanted you to interpret it as something more or less unexpected and game- changing. Greed started to play its role here to drive more money into the market. People hoped magic to go on and on and now it was time for apple watch. It was great, just " great" , no surprise or disappointment yet. So the price would stay ? Nope. It plunged while the launching video JUST START PLAYING, without signalling any good or bad stuff but simply start to unveil itself. You barely knew the product yet but the market just start to go down sharply and unreasonably. What do you do? You understood it is a big day for apple and its stock would be volatile, and it was happened once at beginning of the event, dropped unreasonably, and came back soon. So you decided to stay, hoping another big rally just like when it was announcing Applepay, while you were curious and wanted to see what going on.
You held you position after it dropped 3% and eventually lost all your profit and cut your lost. End of story.
It's the way big money left your in the market because today's launch, as far as i could tell, had no good news nor bad one. All it had is people's greed ,fear, curiosity mixed and generated money for big players. When you are playing with the big money again, think the way they think.