> If coin price > mining cost / 2, it becomes worth it to acquire 51% of mining capability so you can vote the other 49% to yourself, no?
No. The most powerful thing a 51% miner can do is roll-back transactions. The currency goes back to the spender, not to the miner.
But you can doublespend whatever coins you've got, and reject all other transactions, so the effect is the same. (You're right though, I phrased that incorrectly with "vote.")
In other words, the price of any new cryptocurrency (that uses an existing algorithm) should be zero, since a 51% attack is nearly certain.
Well not zero, just below half the mining costs, right? As long as it's below that, you still lose more taking over the new cryptocurrency than you gain. And that's also not taking the price drop post-takeover into account, which affects how much the attacker could actually cash out.
But yeah, it would seem that miners of new cryptocurrencies should expect to lose money initially.
That is ignoring people who do it for the lulz or to prevent competing coins from popping up.
If coin price > mining cost / 2, it becomes worth it to acquire 51% of mining capability so you can vote the other 49% to yourself, no?
But then again, once you have 51% control and everyone knows it, the value of those coins quickly goes to zero. As is probably happening with Auroracoin as we speak.