In short: investors have never been more levered.
And that is only looking at legacy metrics. Recall that as per recent regulations requiring that hedge funds expose gross leverage via Form PF, just the top 50 or so HFs have gross exposure of over $1.3 trillion, which means they are levered massively more than their LP realize, and than the naive NYSE margin statistic indicates.
But that is a topic for a different day.
For now let's just bask in the simplicity of the good old days, where NYSE margin was relevant, and not get too scared by what the true margin level in the market may actually be, especially when one takes into account the leverage on the Fed's own balance sheet.