it doesn't cover you getting disabled so you can't work anymore at the age of 30 after working 8 years.

1600% higher return is great when you work from yours 20s to your 50s/60s and can essentially self insure yourself at that point with it, but as the person you are responding to you is (I believe) trying to say, that's not everyone.

Fair, but given that we're talking about a hypothetical government program, "index-based retirement fund" doesn't imply you're the only one contributing to said fund.