They are willing to pay the inflation penalty because holding the dollars in question provides them something. Generally that means either a sense of security or liquidity on short notice.
Holding dollars is paying a fee for liquidity.
With low inflation like we have seen in the past, risk adjusted it might be a better spot to hold that money relative to other investments. So yes, I hold a small portion of my portfolio in USD for that gain.
If it was not providing that low volatility (inflation spikes like crazy), then I'd be much less inclined to keep my money in USD outside of the minimum I'd need for immediate spending. Because returns are low. So the "gain" is in the risk adjusted return relative to other assets (which could ultimately be slightly negative).
[1] https://ca.finance.yahoo.com/news/public-filing-from-crypto-...