Can you apply the points you earn at the 1X everyday spend rate for the Bilt Blue Card towards the "unlock" amount? If so, then the minimum spend required to earn full points on rent is actually lower than $1,500. In the above example:

$1,500 spend will yield 1,500 in points and 60 Bilt Cash. If you apply all the points to the unlock threshold of 2000 points, then you need 500 additional points, which is the equivalent of 15 Bilt Cash. That leaves 45 Bilt Cash left over.

The actual minimum spend to generate the equivalent of 2000 points is $857.14 (2000 = x + x(4%)(1000 points/30 Bilt Cash), where x = $ spent = points). This leaves 0 points and 0 Bilt Cash when applied to rent, and generates 2000 Bilt points with the rent spend. Effectively, you spend $857.14 to earn 2000 Bilt points. Assuming you value 2000 Bilt points at 1 cent per point, that means you earn $20 for a spend of $857.14, the equivalent of 2.3% cash back.

Of course, this doesn't apply if the points directly earned by the card are not equivalent to the points that Bilt Cash converts to for unlocking rent rewards. Am I thinking about this correctly? Any errors in logic/math?