Duke University professor Harvey Campbell has warned that a 51% attack on Bitcoin could be a more feasible threat than quantum computing, estimating the cost at $6 billion. This figure represents 0.26% of Bitcoin's market cap. The breakdown includes $4.6 billion for mining hardware, $1.34 billion for data center construction, and $130 million for electricity. Such an attack could significantly devalue Bitcoin and erode trust in its immutability, potentially impacting global markets.