...This is probably what caused that spike on btc-e a few days ago.
What's causing the continuous downward slide for the past year and a half tho?
normal market volatility. we've seen it many times before.
So no, you haven't seen this many times before.
2011 bear market lasted like 6 months.
pumping to $1200 in a few months and then crashing 70% for more than a year is not exactly "normal market volatility". It's a pump&dump.