In some cases you can get relevant compression just piping your raw files through LZMA or a similar generic compression algorithm. So for instance taking the fuji raw from this play raw, I get a ~50% reduction in file size from compressing it using lzma, and ~30% using gzip.
The benefit is that you save some disk space and still keep the original file. The drawback is that compression (at least using LZMA) takes quite a bit of cpu time and the files are more susceptible to bitrot and as far as I know most asset management software doesn’t directly support reading compressed files.
It could be a quite nice feature though. At least gzipping files can be done at nearly the speed the are read from a sd card and reading + decompressing a file from a magnetic disk is often faster than reading the decompressed version.