They can - just buy an put on the ETF via your favorite neighborhood broker like schwab, etrade, etc.

Getting authorized for options trading on your account is pretty straight forward and serves as a last fair warning of how much money you're likely going to lose :)

EDIT: to clarify, most of the "exotic" stuff like VIX and XIV (was) are ETFs that are accessible by "regular" investors and hide away the complexities of properly structuring the underlying position to get the exposure to certain aspect of the market. This opaqueness is what makes them so dangerous IMO.

You have to find a broker that will sell them to you. Usually these things aren't vanilla options, they're some sort of quasi-option derivative.

Sometimes brokerages prevent retail clients like in this story below,

https://www.marketwatch.com/story/fidelity-prevents-retail-c...