Rpm, think of it this way. In your example, if he has an equal "nut:bluff" ratio, then our 4bet makes him fold out all his bluffs. (Theoretically) In that scenario, he's folding 50% of the time to our 4bet, and the range that continues we have 40% against.

Do you not see how this is MASSIVELY +EV? With the blinds, our initial raise, and his 3bet there is so much dead money in the pot, the fact that he would be folding 50% of his 3betting range makes us a butt ton of money when we decide to 4bet. And when we do 4bet/get the stacks in, we're winning another 40% of the time!

MATHS!

Pot size after he 3bets: $4.85

If he folds 50% of his 3betting range, we're gaining $2.43

Times that we get the stacks in (assume that every time we 4bet, he 5bet jams with QQ+, AK) we're a 40% dog: pot would be $50. We win .4*50 = $20.
And we lose $25 60%: 25*.6 = $15

$20 (we win) - $15 (we lose) = $5 + $2.43 = $7.43 in EV for every time we 4bet in this spot with AK.

Now obviously, it's highly unlikely he is going to be folding 50% of his 3betting range, and he won't always stack QQ+, AK PF but it's a good enough example to go off of.

If this sounds retarded, or if I did something wrong call me out on it, cuz I'm tired as shit and just kinda threw this together.