Because then rich capital-holders could buy up all the computing power and take control of all the welfare money. Chinese millionaires would end up taking money from needy Americans.<p>Using this system, we ensure that no single capital-holder controls too much mining power over the currency. Every working man is judged on his merits, using a system that is hard for any one actor to parallelize or scale. So many many distinct actors work to secure the underlying currency, and it is safer against large banks or governments.