Bitcoin is slow to transact, energy intensive and if you lose it, you really lose it. You can't just call the bank to get it back.
It is, at the same time, intriguing and a very intelligent design. Nonetheless, it carries the seeds of its own destruction.
If you don't already know, bitcoin is 'produced' by vast data-centres, consuming on aggregate the same energy as the whole of Ireland. And that's with a current minuscule market cap.
Sustainable? Naah...