You can see that bitcoin prices are beginning to recover slightly after touching $ 5900, now bitcoin prices have started to recover to $ 6100 level and are still on the recovery. So I think you should buy bitcoin at this time and do not keep altcoin. The market is bearish and I think you should sell the bitcoin when the price reaches $ 6800.
yes, it will more increase till the end of 2018 as like 2017's end and that's why its price will more double, people should buy more bitcoin and hold it for long term because they will get best profit so holder will more happy about their profit, so that's why it is my opinion to all those people who want to a lot profit in future so they should buy more bitcoin because their future will more secure for their family and that's why they will provide every facilities as they want.