You are completely taking risk for shifting your ADA to ETH but if you think that's the best choice, do it.
Everything has its own risks, we don't need to worry so much about it. Since ETH is a good coin so far, I think it is no problem to sell ADA for ETH. Every coin has the potential to increase as long as it is not a scam coin. I think it is okay if he already considers everything to hold ETH.
Now the potential of ETH is better than ADA, due to the position of ETH is number 2 in the cryptocurrency market. If you want to make a profit in the long run, I think the best choice is spending money for the top cryptos like ETH.