I think the BTC value will be volatile as usual in 2018. I think we will see a new high, trade sideways, and end the year down. I hold BTC as a long term investment but I think it needs to scale. Lightening network will take at least a couple years to be implemented and used at scale. I'm not sure how much market share bitcoin will lose or gain over the next couple of years but I plan to hold my stake for several years due to bitcoin's brand recognition, strong network effects and wide distribution, and the social consensus it has achieved as being "digital gold" or gold 2.0.