The problem is that bitcoin is used by less than 0.03% of the people in the world. Bitcoin energy spenditure is proportional to demand for bitcoin and we should

The problem is that bitcoin is used by less than 0.03% of the people in the world. Bitcoin energy spenditure is proportional to demand for bitcoin and we should expect mining costs to go up drastically if Bitcoin becomes more popular. (Mining costs are proportional to mining rewards, which in turn is proportional to prices, which are a function of demand).