[PopePompous]

Another big problem is that 401Ks have a "longevity risk". Saving as an individual, you must save enough to handle the very remote possibility that you will live past age 100. A pension fund, on the other hand, can safely assume that on average pensioners will die long before that. So a responsible 401K holder must oversave.

[walshemj]

401's have ridiculous low contribution maximums and you don't get any tax rebate unlike the UK where you get relief at your effective tax rate

[gozur88]

In theory you can hedge that risk with an annuity, and anyway you get social security until you die.