the cryptocurrency is not only extremely expensive in terms of its mining costs, but also inefficient in its long-run design.
Mining cost you say, remember when it would cost you nothing to mine bitcoin? Now it costs so much, what does that tell you, that's indeed growth, development, improvement, it shows you it's no longer some valueless shitcoin you simply mine with your ordinary computer. Bitcoin is more than efficient in the long run, if you trace it's growth from 2009 till now, you may then want to edit that part of your post.
That statement of OP makes me feel a little bit discouraged with Bitcoin but then again, the cost of mining the coins is one of the very reasons why the price of Bitcoin has been growing for the past 10 years and this can continue for a long time until 2140. I consider Bitcoin to be a living organism that is constantly looking for acceptable and effective ways in dealing with the many issues affecting it. Unlike many centralized platforms, with Bitcoin changes could not happen without the acceptance of the community hence no one has the power to dictate what can be in here and that's good but it could also mean that we have to wait with patience for developments to take place.