I don't see the connection with $250.
DeathAndTaxes is very good at math.I really like his posts.
For example 65 million difficulty gaining 75% per month for a year results in 50 billion difficulty. The electrical cost even at 1W/GH and $0.10 per kWh would >$250 per BTC.
This is actually pretty funny. The basis of a currency is how many resources must be wasted to make it. I like.
The resources aren't wasted, and that's just a number that one should look at before deciding to mine or buy.
They aren't wasted because you get Bitcoins for them. Ok, sure. I'm not against mining, you know. There is an overhead of wasted resources whenever you try to get any group of people to do basically anything together.