Do you believe that ETH will grow to 2000$? Yes I think most of us believe. Do you belive that Waves cost 30$ per coin? Yes I think that most of us believe to this as well. The difference that it is 3x for ETH, but 5x for Waves. I mean that for me Waves has more potential for Xs.
I think you can buy both in the same time. You don't have to get only one. ETH is amazing, this is the reality. WAVES is also not bad, it has many room for growth and waves can be bigger in the future.