Qubic attack on Monero

This concept suggests that ASIC-resistant PoWs, which are designed to be accessible to a broader range of miners by resisting optimization through specialized hardware, inherently lack security due to their potential for repurposing. In contrast, PoWs that involve significant capital expenditure (CAPEX), essentially creating a financial barrier that discourages repurposing, are considered more secure. This principle underlines the inherent security risks in systems that allow for their mining efforts to be redirected or their hardware to be repurposed for profit in other domains.

A nuanced discussion is also presented regarding the creation of "cash coins" through operational expenditure (OPEX), mainly electricity, which could theoretically adjust in quantity based on demand and technological advancement (as per Moore's law). However, the decentralized measurement of such advancements poses a significant challenge to this model. The discourse extends to alternative PoW mechanisms like Optical-PoW and Chia's proof of hard drive waste, which, while not being ASIC-based, potentially offer a level of security, though their efficacy compared to Bitcoin's approach remains uncertain.

The conversation further delves into the security considerations surrounding merge-mined coins and the unique case of X11 PoW, which incorporates a mixture of different PoWs, including Bitcoin's, suggesting that a hybrid approach could achieve significant security through sufficient non-repurposability. This term is defined as a scenario where more than 50% of the hashrate, including equipment no longer in use due to inefficiency, would benefit more from long-term rewards and fees than from engaging in double-spending attacks for short-term gains.

However, the overarching threat to Bitcoin and similar cryptocurrencies is identified as state-level actors who might seek to undermine these digital assets to protect the relevance of fiat currencies, control over fiat transactions, and the surveillance of financial activities. The defense against such threats is argued to depend on the current operational expenditures of the network outweighing the potential resources a colluding group of states might deploy in an attack. The resilience of Bitcoin, in this regard, is seen as proportional to its perceived threat to state power, with calculations suggesting that even major governments could find sustaining an attack financially feasible under certain conditions.

Moreover, the discussion touches upon the concept of selfish mining, particularly in the context of the Monero attack, highlighting it as a non-threat to Bitcoin provided there is a consensus to enforce timestamp accuracy within a minimal margin of error. This detailed analysis paints a complex picture of the security dynamics at play in contemporary cryptocurrency networks, emphasizing the delicate balance between technological innovation and the constant threat of adversarial actions.