PS: you already made your investment back. Keep 0.5 BTC for the long term. Those who sold at the first bubble at $30 regret it. Those who sold at the second bubble at $270 regret it too. Those who sell during this third bubble at ~$700 will regret it too.
Is that to say that its price is infinite? I mean, at some point, someone will not regret it right?
BTW, I am one who regrets selling at $297 just last week (even though I saw a 3x return), so I don't quibble with that. And, had I held on to it, I likely wouldn't sell now, given its trajectory. My idea was to take profits, let it plummet (as it has before), then get back in. Problem was, it just kept running after I sold it!
So, the challenge is we just don't know where it's going. To say someone who sells now will regret it is dicey at best. As much as I think I agree with you, it's anybody's guess.
TL;DR - 1BTC is not quite infinite, but assuming the bitcoin economy becomes established and grows to a reasonable size, 1BTC today will be a small fortune in just a few more years (possibly sooner, but that'd be due to hype, IMO, rather than real value as a currency).
But with all these disclaimers in mind, I would say I estimate the worth of Bitcoin to be roughly the size of the remittance market, or the gold market, and possibly bigger. So I would say at the very least $100 to $1,000 billion. Divide by the maximum theoretical limit of 21 million bitcoins. That gives a worth of at the very least $5,000 to $50,000 to each bitcoin.
Current demand (presumably resulting from its recent traction in China) is insane. Price is marching straight up and to the right even as I type this.
So, looks like the demand from new entrants is establishing at least a new range. Barring some horrible news, it's becoming difficult to see the sharp drop we've seen before. But, I guess that depends on how you look at it: The new entrants are either feeding the bubble or they're actually transferring wealth into BTC for the longer term. This article suggests the latter:
https://news.ycombinator.com/item?id=6756614
EDIT: In addition, there seems to be a momentum building around BTC with Senate hearings today, more recent VC activity, and more media coverage, etc. I'm wondering if we're seeing a threshold-crossing here, and we'll look back to see this as the moment when BTC's future as a real alternative currency was sealed.
Like what? Will the other currencies ever catch up with BTC? What's the probability of this happening? Wouldn't BTC just become the standard, given it's acceptance?