Thank you guys for replying. There are some very informative comments; probably nothing of ground-breaking news to some of the Bitcoin vets on here, but I gained some knowledge and it has spurred some thought.

I acknowledge the "beauty of Bitcoin" is that it can be held, and it can be transferred, without any need for the trust in a 3rd party (bank or escrow). Basically it has the exact same benefits as cash-money-benjamins with the large added benefit of being able to send any amount almost instantaneously across the world (again, with no bank). This is amazing, it is. And it is the first thing I attempt to explain to one of my poker friends when they ask about Bitcoin. They say that you can basically do the same thing now with your online banking app, and I then attempt to explain how different, how beautiful it is to be able to do that, with no need for trust, with no need for a bank, with no government deciding when to add to the supply and indirectly impose tax-via-inflation on us all, etc.

You can tell me that "the best way to keep your Bitcoin secure is to keep a paper wallet (or an offline wallet)", yes, in the same way that (if I don't trust the bank) the best way to keep my stacks of cash-money-benjamins secure is to keep them in a fire-proof safe in my house. But neither of those options, for Bitcoin or for cash-money-benjis, plays very well towards the utility of the currency; plays very well towards the widespread adoption.

Where I'm coming from is this: These poker buddies of mine, the ones that have heard the buzz-word "Bitcoin", they represent the vast majority of people out there right now, "the curious ones". And I know for the tech-minded, it is not really that difficult to obtain, and hold secure, and use, Bitcoin. But for this group that represents the vast majority of potential users, it is too difficult and too easy for them to be scared away. It's far easier for them to use traditional banking with USD/fiat and the tools already there to do what they perceive as the exact same thing (an electronic transfer of funds).

But...

Once you've gone through the hassle of exchanging from USD to BTC, once you've got an address with some BTC in it, using an online wallet, like GreenAddress (or the handful of others out there), is ridiculously simple, user friendly; done right on my iPhone. The interface, information, and functionality of this GreenAddress iPhone app is super-clean, super easy to use and to explain to one of these curious friends. I can even show them, by giving, and transferring them some bits, how cool it is; their eyes widen, and they love it! (again, not trying to sell anything, I promise)

The problem is: I cannot confidently, or correctly, tell them that they could leave any significant amount of money in this online wallet without the huge risk of it being stolen. All of the intrigue, beauty of this whole thing, to them, they hear this and it's now instantaneously too risky, too complicated to keep their funds secure. Result: they don't buy-in.

Coinbase has implemented their "Vault" as a response towards the concern of trusting a third party with one's significant amount of coin holding. I'll be honest in saying that I haven't completely looked into exactly how it works, and decided if it truly is secure enough to hold a significant amount long-term, but the fact that there is huge effort out there happening to address the concerns and build the infrastructure is, of-course, intriguing.

GreenAddress (and I think some other online wallets) have started to utilize multi-sig (which I now understand there are actually two types; 2of2 and 2of3), and nLockTime, and pre-signed off-chain transactions (correct??) to build-in some pretty neat attempts at increased user control, decreased need for third-party trust. If GreenAddress disappears, I can still get all of my coin back! That is pretty sweet, no? Is it at the level where I can fully trust and transparently see that my coin is at zero-risk of being stolen? Probably not. It'd be interesting to hear more feedback from tryexcept (GreenAddress founder) on this.

It maybe is a technically impossible feat, to create a transparently-provable-zero-trust-necessary-online-wallet, but I guaranty that if it is created the result would be adoption, and to-the-moon, as you guys say.