Volatility drag is defined as the difference between arithmetic returns and geometric returns. It is appropriate to call it "volatility drag" because it is higher when volatility is higher.

It is not a myth. It is real. It is always positive or zero. Bigfoot is a myth. Sigma squared isn't.

In the context of leveraged ETFs volatility drag WILL cost you returns. That cost is no myth. The drag increases with volatility. If you leverage too much the volatility drag will bring returns down to zero?

The difference between zero and positive returns is no myth.