This is so very, very wrong.
I have transcoded literally terabytes of video as both H.264 and H.265, and H.265 consistently is about 2x smaller file size at the same quality as H.264 (even when the H.264 Advanced settings in HandBrake are maxed out). This is far, far better than a 30% gain.
After using H.265, I will never go back to H.264; no regrets about adopting H.265 fully. It is an amazing codec.