That is quite the milestone! It doesn't always equate to people making money in their 401k's though. There are a lot of crappy plans out there with minimal options to invest in.
I made a big stink at a job where their 401k was way under performing. I posted returns from another retirement account right next to current account on the grease board in the office .

it almost started a mass exodus when employees saw the difference. What a dick I am, they changed the plan in short order.
While it seems the stock market is doing ok here in the US, be aware of what is happening in other markets. 30% of our equity positions are in foreign markets.
Check the numbers out:
American unexceptionalism: Foreign markets leave U.S. stocks in the dust
Read "American unexceptionalism: Foreign markets leave U.S. stocks in the dust" on SmartNews:
https://l.smartnews.com/p-78ZrhApW/IRLGCY
It can be found on "Fortune" if you don't have the smart news app.