Volatility has always been built into investing, including index funds.
If retirement is a long way away, then this is a non event. If retirement is close and your 401k was in a target date fund, you are heavily invested in bonds at this point, precisely to deal with this sort of situation.
If you are close to retirement, and heavily weighed to tech heavy indecies, then this will probably delay your retirement a few years. If you’re already retired and so invested, you may have a problem.
I’m don’t know any ultra-Orthodox but do have several friends/family that keep kosher, and all of them are satisfied with just keeping two sets of dishes (although some just have one set and are satisfied that washing them count).
The disposal dishes, cooking in foil, and such comes up when they visit someone like me who does not maintain a kosher kitchen (and even then, only one family actualy cares enough; but, as I said, they are not ultra Orthodox)