You are completely wrong. Difficulty does not drive price. Price drives difficulty. If it is not longer profitable to mine, miners will stop mining and difficulty will decrease. If bitcoin goes up, more people will begin mining to take advantage of it. Difficulty would then go up.
If it cost $80 of electricity to make a $1 bitcoin, well then, no one would mine and the difficulty would plummet. The miners aren't able to demand any specific price. The market dictates that. And yes, they will take a loss if the need the money. But very quickly they will simply stop mining if they are going to keep on taking a loss.
Miners don't necessarily sell their bitcoins. They may to chose to hold. Whether they do depends on the bitcoin price and what they feel like the price will do. It is independent of difficulty though.
Why did the value crash at $32 in 2011, but is holding steady at $120~ today? Difficulty does indeed limit price.
If you could pay $100 for hardware (immediately delivered, no BFL shenanigans) that was mathematically proven to mine 5 bitcoin over the next month, or you could pay $200 for 1 single bitcoin, which one would you pick? Most rational investors will buy bitcoin from the cheapest source. If mining is a sure bet, and effectively significantly cheaper than buying directly, rational investors will mine.
When bitcoin hit $30 back in June 9, 2011, difficulty was less than 1/30th of what it is today. That would translate into $900 per bitcoin today. Anyone who mines can do the math, if bitcoin was worth $900 each at current difficulty mining would be far more profitable than anything else, and buying bitcoin would be incredibly stupid when you can mine the coin for a fraction of the market price.
>The miners aren't able to demand any specific price.
Sure they can. Every bitcoin trader can pick their own price. The special thing about miners is that they bring in 3600 brand new bitcoin every day. As a trader or speculator, you only want to sell bitcoin if you think it's time to take some profit, or if you think value is likely to fall. Miners don't care much about those things, but they do know enough that selling at a loss is dumb. I don't claim to know how many miners hoard and how many immediately sell, but lets say it's a 50/50 split. That would mean that the current equilibrium around $120 is based on 1800 bitcoin entering the system daily, at market prices. If you study the exchanges at all you should be smart enough to realize that 1800 is a very significant amount of coin, enough to push value up or down by $1 easily. Add that up for every single day, as mining is always going on, and you should realize that miners can and do demand whatever price they want, over time. You remove that usual 1800 bitcoin per day flow from mining and value will climb by $1-2 per day on average.
Now, this doesn't occur much because typically value and difficulty DO follow each other fairly well. But if you look at the graph I posted above (
http://www.bitcoinx.com/charts1/chart_large_lin.png ) it should be as clear as air that in the last 3 years, price exceeded the difficulty curve twice, and each time was followed by an immediate correction downwards inline with difficulty. On the other hand, there have been ZERO equivalent corrections during times when difficulty exceeded value as usual. Y
ou can hand wave and explain all you want, but from bitcoin's inception up until today price has indeed followed difficulty.So, none of the miners need to pay for maintenance if margins goes down?
I don't think most do, no. I think the majority are regular people who have a day job and mine on the side. Do you personally know anyone who has quit their job to simply focus on mining bitcoin? Mining is a fairly hands-off task, once you get things running you don't need to spend a lot of time on it, so you would have to have a really serious operation before it made sense to focus on mining full time at the expense of regular alternative income.