When the VIX is historically low and printing close to 10, the MMs are all long options (long gamma and vega). having been forced to buy premium during the entire vol collapse. If they aren't long then most vol players are trying to pick the bottom in the VIX and initiating long gamma and vega positions. Not too many traders are initiating shorts in a low VIX environment. Low vol means relatively cheap gamma and a relatively low theta decay bill. To cover the daily decay, traders need to "gamma scalp" all day/night long. So they are constantly hedging their deltas (produced from long gamma positions) by selling stocks, ETFs, or index futures when they rally, and buying the same instruments when they break. When everyone is doing this, it reinforces the low realized vol environment as the "gamma scalping" makes the trading ranges even "tighter". When everyone is long gamma, there are near unlimited offers on the immediate upside, and near unlimited bids on the downside in the underlying. It's like a death spiral for implied volatitlity.