Holding Ethereum for a very long time does not mean that you can never loose. Investment is a risky venture, you can only measure your risk but you cannot predict what will happen in the future. Most undervalued coins are also very good to invest on.
In a positive approach, even how risky as it is, it's way better that we deal on a risky thing that is worth to put money. In case of ETH, chances that we can get a good result in the future is really possible even how risky it is.
But remember that don't just expect. Make some way too how will get your goal profit in order to ahve a good result in the near future.