Exactly what goldbugs have always claimed about gold, since fiat currencies displaced commodity representational currencies (particularly gold-denominated) currencies.

The thing is, insofar as inflation can be said to “steal” from anything, it's idle holders of dollar-denominated assets. But it's pretty easy to mitigate by moving holdings other than for short-term liquidity into productive assets (which itself promotes real, not merely nominal, economic growth) rather than (or by borrowing against) dollar denominated assets.

Meanwhile, it benefits those with dollar denominated liabilities. Mild, slowly changing inflation (volatility in either price or inflation rate is a problem) isn't much of a problem for anyone in practice, and there's a pretty small audience that is receptive to the scare tactic (and Bitcoin fever has already fully reached that audience.)