Bitcoin is crashing because it was irrational for it to be anywhere remotely close to as high as it was in the first place. Bitcoin is really just a speculative commodity, and not a currency at all. It can't be used as a currency because of its volatility, yet people try to value it as if it were a currency.
This crash is 100% normal, it should not surprise anyone, and it is only beginning, with plenty more room to fall. Bitcoin does this over and over again. It will crash down and stabilize for a while (maybe a couple years) and then have another bubble where it crushes previous all time highs.
Basically you only want to buy bitcoin when it is boring to buy bitcoin... and even then, it's still an extremely risky investment.
I would disagree with you. I think that Bitcoin is heavily under-priced right now. Bitcoin is being used as a currency by around 10 million people, and still its market cap is below $50 billion. On the other hand, the market cap of the Swiss Franc, which is being used by less than 8 million people is many times that amount (including bank deposits as well). So in my opinion, the current dip may be a temporary one, and new heights may be reached in a short time from now. Sell your coins now, and regret later.