Originally Posted by Andy

Others have already pointed a major flaw in your calculations - the ability to save $1500/mo as an O1-O3, but let's run with the $1500/mo earning 7%. That comes out to ~$761K after 20 years; you opted to aggressively round it up to $800K.
An O1 under 2 grosses $3034.80/month. I suppose if he lives on ramen and has a bicycle for transportation, he could bank $1500/mo but it would be a miserable existence.

Still, you're talking tomorrow's dollars and are ignoring the effect of 20 years' worth of inflation.

Instead of using $18K/yr, how about someone use the 2017 match of 5% plus 5% individual contribution. Then compare that to a 20% reduction in retirement pay. I haven't worked the numbers but I'm sure they're out there somewhere.