A medium- or large-sized botnet is able to provide more computing power than the most powerful supercomputer on Earth. The larger the botnet, the more power there is available to an attacker. The entire processing power can be used to perform miscellaneous tasks, not only for free, but also safe from the attack. The most powerful computer to date is the BlueGene/P, an informatics structure developed by IBM in collaboration with the US Government. It can deliver a computing power of 1 PFLOPS sustained and 3 PFLOP peak.”]
Source: https://www.bitdefender.com/blog/hotforsecurity/virtual-entities-spreading-real-troubles-botnets/