Piracy: ꜱᴀɪʟ ᴛʜᴇ ʜɪɢʜ ꜱᴇᴀꜱ

Yes, but the point is keeping the quality the same. If you reencode a 5000 kbps x264 Blu-ray encode to 3000kbps x265 you will have visibly worse quality.
If you encode the corresponding Blu-ray remux with x265 to 3000 kbps the result will likely be nearly indistinguishable from the 5000 kbps x264 encode.

For OP: I also prefer smaller releases so I download mostly h265 WEB-DLs. They are usually around 3000-5000 kbps (1.3-2.3GB/hour) and look fine (especially as they usually come with HDR).
Redownloading WEB-DLs in the right size will give you the best quality for the small size (and saves energy, depending on where you live).

1. This number is taken from the Wikipedia page, and represents a lab setting from totally uncompressed to full HEVC encoding. It's not representative of data savings that you get from one video codec vs another, which is likely less than 4-6% between something like VP9 and HEVC... The 25-50% of completely fucking laughable in a realistic setting and you look like and idiot for bringing it up.
2. It's absolutely an overestimation by every conceivable metric available.
3. You can encode to whatever you want, but if you take a VP9 encoded video and re-encode it, you may only save 1% and it will take several hours to encode. There are even situations where you will save nothing, or the resultant video file is actually larger even with HEVC.

It's zipping a zip file. Endlessly re-compressing things doesn't yield positive results in the way you describe.

I don’t understand what you are arguing?

If you’re arguing that downloading remuxes and only flac is foolish then yeah, 99.8% of the time h264 and 320 mp3 are going to be indistinguishable on most setups with most content. H265 will be the same on like 99.5% of setups with slightly less content and will save tons of space. Sure. But this assumes the lossy encodes were done properly from a lossless master

if you encode lossy to lossy it will result in visible and audible distortion of the image and audio. Sometimes it’s minimal, sometimes it’s quite bad, sometimes it’s masked by your equipment, but it’s always there. Further, you’d spend more money on electricity running your cpu on full blast encoding terabytes of video files when you could simply just redownload your library in whatever format by someone who knows what they’re doing (if you’re so concerned about space and don’t care about quality go av1)

But you do you