if ethereum goes up 1500% in 2018 meaning if it goes to nearly $20,000 then I will officially lose faith in the cryptocurrency  world in general because ETH is the shittiest coin that has ever existed. full of bugs, lots of issues including serious scaling issue, lots of shilling and lots of spam-advertisement with lots of false information. such a coin should not even be worth more than $20 let alone that high.

as for bitcoin's 500% which means going to $78,000 from current price. I don't think it can happen because we will have a lot of issues to face with. mainly the scaling issue and the spam attacks against bitcoin which is the only reasons keeping the price back at the moment.