"My attic is well insulated so whether it is 150 degrees up there or
105
degrees up there, is it really going to make the INSIDE of my house any

cooler?
I mean the way I look at it, if you have enough insulation in your
attic
the heat isn't going to penetrate all the way down to your ceiling
anyway, so whats the point of using these pw vents? "

If it were perfectly insulated, that would be true, but normal
insulation is far from perfect. That's why the temp on the other side
of the insulation makes a difference and one of the reasons why
heating/cooling systems run more the bigger the temp difference.
Proper attic ventilation will help reduce the temp diff and result in
less cooling demand on your system. I think one of the bigger
differenced is with proper venting, once the sun goes down, the heat
gets removed from the attic quickly instead of staying trapped there
for many hours.

As Joseph pointed out there are other reasons for proper venting, ie
moisture, roof life, etc. IMO, for most applications, the most
effective system is adequate soffit vents and a ridge vent. With a
fan, you have to be especially careful that there are adequate intake
vents for the fan capacity. Otherwise it can suck cool air out of the
living space through recessed lights, cracks, outlets, etc.