You must be compromising on the audio or something.
I’ve got 1080P rips that are over 10Gb, never mind 4K.
I agree. I'd say a good 1:1 blu-ray rip is still 20-40GB, but each to their own. If they can't see the difference between a 5gb rip and a 50GB rip, then its a hell of a lot of hard drive space saved. I can personally see the difference is startling in terms of clarity and level of detail.
Some films just are very soft though, regardless of the bitrate. I was quite dissapointed in the new Aladdin film which was so soft. Also preferred the SDR colour grade.