$120 isn't cheap? 11 million shares and a global economy that we are only hoping to get a small fraction of a percentage of ? $120 is VERY cheap when you factor in the market, incoming VC money, low float, affect on currency/monetary policy, etc. We are talking about a revolutionary game changing technology. Can you come up with something better? 
True, compared to world economy $120 is still cheap. But world domination takes time. Historical growth rate of bitcoin is somewhere around a tenfolding every 1-2 years. That just happened, so chances are low it will happen again anytime soon. A black swan event can ofcourse always occur, a single ambitious billionaire jumping into bitcoin can do the trick, so always be exposed to bitcoin with a decent percentage of your capital.
That being said, chances are higher for it to correct after a bubble than for it to launch into a new one shortly thereafter. So a good portion of your bitcoin capital on the sidelines is rational in my opinion.
I guess it is safe to say that none of us know. But in danger of missing a Black Swan go by I would rather sacrifice some future "profit" or holdings of BTC by trying to buy in later at lower prices, with just holding at what I see to be a great price - now. But I can say, it is wise to have capital available to buy more in later should that occur. But it sounds like you are trying to rationalize the greatest social experiment in the history of our civilization. Think about that.
Now, if it jumps up $100 or $200 in a day, your going to be there sitting in cash. Moral...
Don't try to time a Black Swan.
