If you believe the rule of law and ~general financial stability of the US will persist just keep on investing regularly and ride it out. Markets have a long history of bouncing back and they will keep doing it until they don’t. When/if that happens your retirement dreams might seem quaint compared to the global socioeconomic reality. The people who could sustain the most near term pain are those who have already retired and are living in a fixed income.
Index funds, generally. Ideally something more diversified than just an S&P500 one, but honestly historically it usually hasn't made _that_ much difference in the long run.
Assuming you're talking decades away, it usually all comes out in the wash.
Now, where you should really potentially worry is if you were retiring imminently and needed to pull out a bunch of money to make that happen. But if you're retiring in 20 years or whatever, and, say, the S&P halves next year, is it really, in the scheme of things, _that_ big a deal?
If you could time it perfectly, you could come out better by selling now and reinvesting after the crash, but bear in mind that you probably cannot time it perfectly. People were predicting the 2008 crash imminently from about 2004 on, say, whereas the dot-com crash went from dark mutterings to chaos in a year or so. These things are very hard to time.
As long as you have a decent capabilities and range, and don't keep all your savings in your employer's stock (either real, or, more stupidly, imaginary "options"), stupidity of your employer will only affect you in the short term. In the longer term, you're likely find another one. It's not fun, but it's how it goes.
Like everyone else, wait until the very last second, just as the market peaks, to unload your assets. Before the institutional investors and insiders beat you to the punch.
Spend well below your earnings, max out tax advantaged savings plans, save aggressively, invest lazily (standard blended portfolio or close to it probably will suffice) and 20 years should be enough to make a decent nest egg.