While it's rather disheartening to see the price/value of GNT slowly crumble to a fraction of what it was once worth, this is the case for every and each alt coin.
Therefore, I would not sell these tokens under any circumstances. Keep holding and one day (hopefully sooner) we will all be thankful we did!
Yeah, part of me wishes i'd sold the top to buy this drop but we can only learn & move forward. What I see happening is Bitcoin rallying probably sometime this year, this will really strain altcoins. The alts with a purpose & determined developers will prevail & eventually rally themselves while opportunity coin developers will abandon their alts & dump for BTC. I hope this does not happen & everything rockets upwards simultaneously, but am preparing for such, by researching as much as I can about the coins & tokens I hold.