> If hash capacity were traded on a perfectly competitive market, then it would always make sense to rent 51% of the capacity at market rates "Renting 51%" (of

> If hash capacity were traded on a perfectly competitive market, then it would always make sense to rent 51% of the capacity at market rates "Renting 51%" (of any global market) and "at market rates" are mutually exclusive. > There is no equilibrium point for transaction fees where this attack becomes uneconomical. The counterforce against doublespending is not transaction fee but cost of ownership of mining equipment. Some other arguments against your conclusion: - As mentioned nearby, for big transactions you want to wait longer than 6 confirmations. - Also, as recipient you might want to distribute huge payments into smaller ones distributed over time. - It's in the interest of mining capacity lenders to make sure you don't get 51% because it renders their equipment worthless in case you are successful. - As you correctly stated, low prices will lead to lower hash rates (and higher prices to higher rates). This means actually that bitcoin will be more stable (it's harder to obtain 51%) if prices rise. There's an equilibrium on that side as well! That is, if double spending is what you're worried about.