Sure there are botnets, but there are also billions of CPU's in home computers. Can't say that about ASICs. Which is more centralized?
Yes there are a few ASICs in consumer hands, but those are nothing compared to the farms in the factories of the ASIC miner builders. Now think what would happen if one of those companies was bought out by US gov?
51% attack on an established CPU coin? Near impossible due to
decentralized nature of CPU mining and high cost of CPU. (made it bold, CPU mining is decentralized despite some botnets)
51% attack on Bitcoin? Very possible if you have the funds (a few billions should be enough).
yes and those billions of cpus, a significant proportion can be botnets, and cloud servers, which are far more powerful.
Eg I have cpu mined prime coin, on EC2's and that became impossible very quickly to make a profit. People with access to low cost mass computing, keep out the home cpu as its not economically viable. So those billions of home cpus will hardly be used outside of botnet.