To expand on your comment: when a small number of users with a large store of bitcoin sell out, they are selling into the hands of hundreds of small scale owners who have diverse motives for holding the coins. The chance that they all cash out together diminishes because they are using the coins for individual purposes. You're witnessing the growing spurts that will shortly settle down.
Bank run on bitcoin will happen when people feel it's totally broken. There were already a couple of major bugs in Bitcoin software itself: in 2010 a transaction was created with 184 bln BTC due to an integer overflow. Was fully fixed in 10 hours. Recent bug with a hard fork of the half of the network was fixed within a 3-4 hours.
When stuff like that happens, some may freak out and sell their BTC. Speculators who still believe, will do the same and then buy at a lower price, recovering the market price. If the problem is fixed, in 24 hours no one will notice the difference. Luckily, Bitcoin is getting more and more decentralized and stable as more people are involved in development and more money is at stake. This motivates everyone to protect the system and act quick to fix the issues.
Do not define consistent growth with volatility. As Bitcoin is getting more valuable in the eyes of more people, its price necessarily must grow. If it doesn't, it means only one thing: everyone bought (or didn't buy) all BTC they wanted and not much trade is happening.
Draw the trend line and see the variance of 2-day average around that trend. The volatility is silly compared to how much you can gain if you invest early.
By "volatile" do you mean "growing" here? Because that's very expected when more people are getting Bitcoin. Bitcoin's potential is probably millions of dollars per Bitcoin. That will only happen if a lot of people use it.
the larger the price per bitcoin the lower the volatility, over $100 and a $5 difference a day is 5%, if/when BTC reaches $1000 then even £10 variation a day is only 1% and is much easier to account for.