You don't have to wonder. Adi Shamir, the S in RSA, analyzed the block chain up to block 181,000 and determined that 78% of the coins are not in circulation. They are either being horded by miners and early adopters, or they are lost. Back in the days when mining coins was easy with desktop CPUs, people would routinely delete wallets with thousands of coins, because they weren't worth anything. Theoretically, 10 million bitcoins exist, because that's how many have been awarded, but realistically, from what I've heard people say about the early days, half of them could be lost until we get the technology to brute force SHA-256. Among the existing coins, miners are holding onto a large chunk. Will they sell at $100? Probably not. Why should they? They've been mining since bitcoins were 1 cent, so why didn't they sell at $10? That's a 1000 fold pay off. What difference does $100 make? That's just another 10 fold. I think a lot of those people are true believers in bitcoin. They envision a world where bitcoin becomes a standard currency and they can use it without cash out fees and taxes. Oh yeah, taxes and regulations, that's the other thing holding them back. You can't cash out millions of dollars worth of coins without getting noticed, and you stand to lose a big chunk of that in taxes. So I don't predict a huge sell off by bitcoin horders. Not at $100 or even $1000. The more it's worth, the more incentive they have to hold their coins until they are an established currency, and then they will circulate them within the burgeoning bitcoin economy. As long coins aren't being traded for dollars, they won't lose value.