The FUD in this article is strong. Nothing ever grows exponentially over long time periods. The energy expended secures the network from human corruption/interference. This is the cost of eliminating corruption. Context is also needed. What is the equivalent energy expenditure and other costs needed to run the global financial infrastructure? Include buildings, transportation, electricity, fuel, salaries, legal costs....
Yes, that's true. For example, sometimes things suffer a catastrophic collapse. Other times, they may just slowly fade into irrelevancy.
Regards.