Just look at history. Since you've only been trading for a year, then you won't have much experience with the Mt.Gox disaster several years back. The price of bitcoin (i believe around jan 2014) hit an all time high of close to $1200. Then one of the biggest exchanges on the planet (Mt.Gox) shutdown overnight as the founder stole everyone's coins. Everyone lost faith in the market and the price dropped as low as around $200.

So this is why you should hodl ... if the price goes down (for example back to $1000), then you have the chance to buy some relatively cheap bitcoins. I certainly wish I had bought a lot more coins after the Mt.Gox fiasco!

HODL.