Yes bitcoin and altcoins are in huge dip and you can buy as this is the perfect time to buy any crypto coin you will get profit this is 100% sure.
Look after any safe coin and buy this will easily give you 5* return if you hold coin till 2018 end . You need to diversify your coins and buy different coins according to budget do not step in into one coin which might take some time to grow we cannot predict the future.