i dont agree on the part that bitcoin has no practical use but i somehow agree on the part that bitcoin could be damaging to the economy .
bitcoin do have practical use and that is for paying , buying , for investing , trading , etc...
bitcoin could be damaging to the economy in the form of bitcoin mining where too much heat is released from mining hardware . bitcoin can also damage the economy if bitcoin is used in a wrong way due to its anonimity feature where you cant be easily traced if you'v done something wrong .
I do not think that the amount of this heat can bring some damages. It even sounds funny. Bitcoin has a practical use for people that trade it and make money holding it for long as well.
Bitcoin is not only a place to make money, but Bitcoin can also provide new knowledge just like you do exchanges and can teach you to be able to train the patience you have so that you will not be easily affected by anything.