The development of cryptocurrencies. No future?

What do you think about the future of crypto currencies? To my opinion in the existing state they have no future.
Mining of such currencies spend huge amount of resources without no obvious benefit. Just think that millions of machines throw their computing powers and electricity into toilet. Yeah they produce working places in IT sector, advertisement, power generation sector but they have weak connection with producing of real goods. And with regard to it they look like a soap bubble. So development of such currencies is based on advertisement of fast and good profit. So the market attracts many people with idea of giant profits in short period. Such people are blood of the crypto currency economy. No people - no chance to covert crypto currency into real money. No demand of crypto currency because its equivalent of nothing. Just think that huge profits is a trap for investors that is made by mining farms, exchanges, crypto currency systems and etc. Don't you think that bitcoin still exists and beating the records because there is no good crypto alternative? May be in such context the crypto currencies connected with scientific developments have a chance? For example if they make an option of transfer crypto coins into no voting shares of companies that are conducting scientific research.