He's talking about the "Admiral" class of funds which have lower fees but higher minimums. (And most are $50k min, not 500k). Most of these funds can be bought at lower minimums too, they just have higher fees.

I'm invested in Vanguard 500 Index Fund Admiral Shares, and the minimum investment is $3000, with fees of 0.04%. Those are pretty low minimums, and seem to me to be exceptionally low fees, and the average annual return is 13.94% over the last 10 years (before taxes).

I think OP is referring to the "Institutional" class of funds. They have much higher minimums because their target market is pension funds and large 401(k) plans that invest using pooled accounts.