Monthly S&P 500 Flirting with Significant Fibonacci Extension

My last idea was that the stock market might burst up from a descending channel and move up decently. It did. Now I'm starting to grow wary: earlier than I hoped. I think what it's doing now - advancing bit by bit without a pullback - is convincing people who missed the bottom that it's safe to buy now. I don't think so it's so safe now. 2045 was safe.

My biggest concern is after quite a lot of years in a bull market - and one long sustained run since late 2011 - the S&P 500 is having trouble at the 2.618 Fibonacci extension level: The ES1! contract shows during the last eight months volume was much heavier on the sell months than the buy months:
I suspect the market is undergoing distribution. I don't know what could spur this market for much longer. I'm pessimistic now.