As much as I would love that, probably they don’t have their fortune in cash savings but most probably put it into diversified investments of some sorts.
I’m guessing both, so they get returns and still have an “oh shit” fund. I doubt it would be good for the oligarchs, at the very least.
Venezuela can do hyperinflation because they have a more ideologically driven elite who will ride out the turbulence. No such luck for Putin; he’s a neofeudal lord and has to keep palms greased like it.