First you overestimate by assuming that all mined coins are sold. I think 80%+ are kept. Rerun all those number with only a fifth the coins for sale.
I've addressed that. if that's correct it makes it an even worse bubble.
$170 million in 5 years is actually a really small market on a global scale. For a comparison that might be close to home -- Dungeons and Dragons brings in $1 billion a year. And yet, very few people actually ever spend any money on it. M:TG doesn't release their stats, but people have estimated it could be greater than $5 billion a year.
ok, if you think 170 million $ will come in (or a lot more in case you're speculating on a rising price), you are set.
I don't think very many people realize though what kind of numbers are required to sustain this price.
So if bitcoins only become as big as magic the gathering (which, lets face it, not many people have heard of), we may see $25 billion in the next 5 years. By your simplistic calculations, that would put the price of a bitcoin at > $3,000.
I don't understand this comparison. people spend money on games.
they expect returns on investments.
fun fact: the bitcoin economy will be as big as antigua and barbuda in 5 years ;-)