You should be following the flow chart in the wiki if you're trying to max out your net worth long term. Everything in the market is on sale right now and you don't need to take anything out of retirement for 30 years so this year's losses are, frankly, irrelevant.

The 20k you didn't put in your 401k this year cost you $94,869.82 in 30 years assuming a 6% return annually which is lower than what many calculators assume.

It might bite them in the ass when they don't have access to the funds if they need them like they would of they put this money in a retirement account.