It even seems to me, from where I stand, that if the Ethereum investors started discussing this possibility publicly, then this discussion alone might make Bitcoin investors uneasy, and some of them might start migrating to Ethereum.

Is this a far-out prediction? Thoughts?

The cost of a 51% attack has been estimated to be $6–$20 billion [1]. This is only 1.3%–4.4% of Ethereum's current market cap. And it is only 0.5%–1.5% of its potential growth if Ethereum knocks down Bitcoin and conquers its full share of the cryptocurrency market.

If the Ethereum stakeholders pool their resources, they could thus easily afford a 51% attack against Bitcoin, and could profit quite considerably from it.

[1] L. Nuzzi, K. Waters, and M. Andrade, Breaking BFT: Quantifying the Cost to Attack Bitcoin and Ethereum, SSRN.

The term "Goldfinger attack" isn't standard in cryptocurrency discussions, but it may refer to a scenario involving manipulation or undermining of the cryptocurrency markets or consensus mechanisms. Assuming you mean a theoretical attack where one cryptocurrency, like Ethereum, could leverage its resources to negatively impact Bitcoin, here's some relevant context:

1. **Understanding the Dynamics**: Each cryptocurrency operates on its own network and has distinct consensus mechanisms (Ethereum primarily using Proof of Stake as of the Ethereum 2.0 transition, while Bitcoin uses Proof of Work). The two networks are fundamentally different in their operational design, purpose, and communities.

2. **Market Competition**: Ethereum and Bitcoin serve different purposes. Bitcoin is primarily viewed as a digital gold or store of value, while Ethereum aims to be a platform for decentralized applications (dApps) and smart contracts. Any competitive actions between the two would more likely happen through market dynamics rather than an overt attack.

3. **Interoperability and Integration**: Instead of mounting an attack, there is more collaboration happening in the crypto ecosystem. Many projects aim to create bridges between Ethereum and Bitcoin, allowing interoperability rather than conflict. Additionally, Ethereum's developers focus on enhancing their platform through community-driven updates, not undermining other cryptocurrencies.

4. **Third-party Actors**: Any potential attack on Bitcoin would more likely come from malicious third parties rather than Ethereum as a platform. Attackers may exploit market vulnerabilities or attempt coordinated selling strategies, but this isn't about Ethereum as a network actively seeking to undermine Bitcoin.

5. **Sybil and 51% Attacks**: If we consider technical attacks, Ethereum cannot simply mount a 51% attack on Bitcoin due to its independent blockchain and consensus mechanism. A successful attack like this would require exceptionally high computational power and resources, which is prohibitively expensive and impractical.

6. **Community-Centric Nature**: The cryptocurrency ecosystem is known for its community-driven governance and ethos. Direct attacks may lead to backlash not only from the target (Bitcoin community) but from the wider cryptocurrency community, which generally advocates for growth and cooperation in the sector.

In summary, while it's theoretically possible for one group to attempt to destabilize another currency’s network or market, the dynamics of cryptocurrencies like Ethereum and Bitcoin suggest that outright attacks are unlikely, and the more probable scenario involves competition and technological evolution rather than direct aggression.

These are very good points. And I think that you are right that the Ethereum community would not support an attack as things are right now.

However, this could change over time if there is indeed up to around a trillion USD on the line. If Ethereum stakeholders (investors) realize that they potentially have the power to bring down Bitcoin, some of them might start to become vocal about the potential for an attack. Maybe this talk alone could even start making some Bitcoin investors uneasy, and make some of them migrate to Ethereum.

You state that the purposes of Ethereum and Bitcoin are different, and that is a good point. But they also share some of the same purpose: being a decentralized cryptocurrency. And if Ethereum can bring down Bitcoin, this could make Ether the new number one cryptocurrency, which could massively increase its value, in theory.

So your are probably right that Ethereum and Bitcoin cooperate somewhat at the moment (and that they specialize in somewhat different markets). But this could slowly change once some of the Ethereum investors sense this opportunity. And if Ethereum could truly stand to gain around $0.4T-1.3T from a Goldfinger attack, then it only requires a fraction of the investors participating in order to be able to fund and profit from an attack.