With most 401k plans, you can choose what you invest in to an extent. You can put it in bonds or other investments if you want.

Until someone can come up with a better option though...

Note that a pension plan that invests for you blindly is no better - either the returns are so bad that they are a scam, or they are investing in stocks anyway and so you get the same results but less control. Similar for things like social security, they are either worse options or you need to pump stocks.

This is what financial capitalism and "democratizing finance" has meant in practice. Rich people have access to different types of investments, and by the time those trickle down to common investors the juice has all been squeezed out. Whatever the trend is, by the time you hear about it the market has already been arbitraged by faster investors with more resources.

We are not going to come up with a market-based solution to fix income inequality. The solution, as much as people in the dwindling middle class resist it, is a strong social safety net coupled with a hard reset on taxation and housing policies. Nobody should be homeless, nobody should be allowed to starve, but you might have to accept that your 401K goes down in exchange for a government guarantee of housing and food.

This is hard for people to accept because they currently have equity in their home or a 401K to save them from starving. But those are transient, individualistic solutions. You can lose your house. You can lose your 401K. Society should be taking care of each other in a broader way than letting everyone accumulate a little, private pile of money.

You don’t have to invest your 401k in stocks.