The issue with saying how much a 51% attack "costs" is that ALL cryptocurrencies (and, really, ANY currency) is just based on the trust that the currency has "value", meaning that it would be accepted as payment for real goods and services.
A 51% attack on bitcoin would be easily noticeable. If a 51% attack was really "viable", it means that essentially bitcoin would have $0 value, because all of its value is based on the trust that the blockchain is real and verified. The community at large would essentially just ignore the rogue chain, or rather probably boost other existing resources to back it out.
A 51% attack on bitcoin would be easily noticeable. If a 51% attack was really "viable", it means that essentially bitcoin would have $0 value, because all of its value is based on the trust that the blockchain is real and verified. The community at large would essentially just ignore the rogue chain, or rather probably boost other existing resources to back it out.