I think if you define "safe" as a legitimate investment, then we can ultimately say that it is safe. On the other hand, if you meant "no risk of losing money", that's not what Ethereum, other altcoins, or even bitcoin investment looks like. The market depends on the demand of supply (as always), but here, the volatility is high compared to other investments. Furthermore, I think it'll be preferable if you know yourself if ETH is worth investing for. Research more about it, after that you can make your decision.