I think they usually say that they are focused on alpha while minimizing beta, i.e. don't compare us to the S&P or other indices because we are market neutral. And in my experience, the large, old firms that I am personally familiar with do in fact have beta very close to 0 in their main funds, so on that front at least some firms do deliver.

This doesn't necessarily make the product a good idea even for people who can get an allocation, however. For example, because most (all?) market-neutral firms engage in active trading, a US UHNW person living in a high-tax state will generally have to pay around 50% of each year's gains in taxes. These taxes will have to be paid whether or not they did or were even allowed to withdraw any money from their investments that year, so a gain of let's say 12% becomes 6%, which may have to come out from some other source.

Anecdotally (can't say how I know), many firms did very well in the 2020-2021 Covid crash, also its quite cheap to say buy 50 million in far OTM puts to guard against black swan events. It's far more likely that a slow slide in SPY will show some Beta correlation than anything else.