I'm not planning on Social Security being around by the time I'm old enough to tap into it, and I'm also not planning on having any kids to bail me out when I go senile, so yeah I'm putting a lot into my 401k. I think a lot of people my age (turning 30 next week) are feeling the same way, so I wonder if it's younger workers driving this trend.
I read this a lot. Why do you expect this to be the case? Social Security may become unable to pay the benefits that you're expecting at some point because the input from workers will not be enough to pay those benefits. But that doesn't mean it will pay nothing. It will just pay less. You'll still get some payments.
Large adjustments were already made to accommodate the baby boomer generation. That's why we have a $2.8 trillion-dollar trust fund. With current demographics, we should be able to pay 100% of promised benefits until the late 2030's. Afterwards, with a pure pay-go system, we'd only be able to pay ~80% of benefits.
There are simple fixes that could dramatically extend the reserve depletion date to sometime in the 2050s. Not doing so is purely a political question.
Trust fund stats: https://www.ssa.gov/oact/STATS/table4a3.html