Personally, I use software I purchased to reduce some vids to save space by converting them using a 4:4:4 high profile (removes unnecesarry pixels) at a variable bit rate. However, that takes a lot of time & PC usage so I tend to just convert/downsize 4K vids by manipulating the kbps and/or fr/sec. Besides, 4K is overkill and is just too big so I reduce them to 1080p and save a ton of space. The video quality loss is there but not enough to make it look bad at all.
I recently reduced 75GB of 4K to about 35GB using the following method:
4K video at 60fr/sec @ 30,000kbps
reduced to
1080p at 30fr/sec @ 6000kbps.
Also, I sometimes will take a 12,000kbps 1080p and downsize it to 5000 at the same bitrate to save space with no discernible quality loss.
On average, those methods cut the file size in half and the video is still sharp.....just not 4K sharp. Just remember to check the video for pixelation BEFORE deleting the original file.
Ultimately, if you plan on collecting, save money for ext. HD space. Oh, and word to the wise:
Don't go cheap. Bite the bullet, get the 10TB+ (I always use seegate) and thank me later.
BTW, only ever had 1 seegate crash and that's because I dropped it. Actually, it still works....sort of, kind of.