Why because you have to mine it? Im not a miner, but mining gives coins some value. With your logic, I guess bitcoin is a waste of energy too, since it has to be mined.
Yup btc is eco disaster and it won't last long
ecological aspect have little impact on things, money involved into it have a bigger impact. With the money spent on asics for BTC, i don't think it will fail soon and if it fails i don't think it will be because it's not eco.