I don't think GoPro went down because of the threat of the patent. Rather, investors are afraid Apple will start to compete against GoPro. People are seeing the patent as a possible product roadmap not a legal threat.
Before GoPro was even a known brand you could easily buy extremely similar items (small plastic cameras with one-two button(s)) off of eBay straight from China which cost under $50. They often came with generic stick on clips for motorcycle helmets and similar.
This entire market existed for years before GoPro suddenly appeared. All GoPro did was package up the generic product from China, increased the price by 100%, and then used all the extra revenue to buy a ton of adverts.
People often like to claim that GoPro won because it was optically better, but that just isn't accurate. Up until maybe the HERO3+/HERO4 (2013/2014) the line was actually quite behind some generics. The only reason GoPro even got their act together was that some other named vendors started getting into the "action camera" market.
Even today GoPro seems insanely expensive, for the price of a single GoPro HERO4 SILVER[0] with a basic plastic case you can buy the same spec camera on eBay for $65 [1] with enough money left over for a [bad] DSLR by Canon/Nikon/Sony/etc [2].
[0] http://www.amazon.com/GoPro-CHDHY-401-HERO4-SILVER/dp/B00NIY... [1] http://www.ebay.com/itm/Black-SJ4000-Full-HD-1080P-Waterproo... [2] http://www.amazon.com/Sony-Interchangeable-Digital-Camera-18...
Hindsight is perfect, you just get all the survey results from the buyers and sellers and see what the common reasons for buying/selling were. Then you post an article before the closing bell that same day. Easy.
I've worked with traders, trying to implement the system they think they use. They had a system of indicators and said they traded according to them but when applied mechanically to trading data it didn't make a profit.