140Gb System Storage and just 80Gb of Docs

Dear Apple Community

I have an HD of 256Gb. I do not use Time machine, I have everything in one folder within "Documents", no duplicate files etc...I went through many posts, forums, websites, etc...

I have 83Gb of Documents and 140Gb of System storage. Applications take 8Gb and a VM uses 28GB.

Simply put, in a HD of 256Gb, 100GB of the storage are for "System Storage" (39% of the total storage).

Is there any REAL solution to reduce System Storage

or

is there any SIMPLE explanations why this happens?

All solution like several "Cleaner" apps gave no results.

Should I just make a clean installation of the OS?

Thanks in advance.