@franky1, I'm very sorry if I misunderstood you. But you first of all start your reply by saying "here's the thing," which already seems to imply at least that you don't necessarily disagree with my point. Then you go on to write that there is in fact an even better way for attackers to target Bitcoin and make a lot of money. You follow that up with to comparative statements, saying that you way is better than the 'Rival Goldfinger attack,' and that the latter is more costly, slower, etc., than your way.

This is a complete change of the conversation. Now we are not talking about the feasibility of the 'Rival Goldfinger attack,' but of its efficiency compared to some arbitrage venture, that you have by the way only brought up in the same post. (You have talked about arbitrage before, but as I recall, you have never stated that it is a more lucrative way to target Bitcoin as part of this discussion.)

Why do you even bring up this arbitrage venture as a better way to target Bitcoin if you are still not agreeing (against the conventional wisdom) that a 51% attack would be severely harmful to Bitcoin? 

But oh well, apparently bringing up your arbitrage venture idea was only a somewhat unrelated tangent to the discussion (?), and you still think that a 51% attack can't be profitable (given that the value of Bitcoin doesn't crash).

You seem to be hung up on the confirmation time. But even if the attackers exchange their BTC back and forth for USD (rather than trade them perhaps more quickly for tokens or ETH), you still agree that it only takes a few days at max for each confirmation. Now, whatever confirmation period there is, this is something that all traders have to deal with. Yet there are still being traded BTC worth billions of dollars each day, despite these long confirmation times! You must agree that with enough money and backing, there is nothing stopping the attackers from trading many millions each day on average (and in principle, it seems that they might be able to trade upwards of billions).

So do you see that we don't really have to discuss the current confirmation time here; not when we are talking about a long-range attack that could rewrite months of the ledger?

Also, you seem to want me to research your arbitrage venture idea, which I definitely want to do if it indeed only takes 10 minutes, and constitutes a business that completely blows all other investment options out of the water, which, you must admit, you make it sound like. I'm sure more people on this forum would love to hear more about this idea, even if it is only half as good as you make it out to be. (But maybe you should create another discussion thread for it, though, if it is not directly related to this one?)