I think Ethereum is ideal for long-term investment because ethereum has high demand and volume in each exchanger, I personally continue to add ethereum investment because I believe ethereum will provide a lot of profits in the future
I'm sure that the Ethereum developer company will exist and will feel good in foreseeable future. I'm not so sure about Eth coin itself tho, it doesn't burn and has no limit (like etc for instance).
For me thats a bad sign in long term investment. It may grow x2-x3 in this decade only if eth will become like next fiat and will widen its usability a lot