This.
And even if you do a clean install, might gain back space for only a brief time. Ie. the system will start creating log files, caches, temp files, etc.
Recently ran into trouble with my user account and could not track down what was causing it. Not thinking clearly (ie. should have just created a new account and move my files from old to new), went ahead and did a reinstall over the top of existing install. Picked up about 6GB of space, but that eventually crept away (above paragraph, plus any new smallish files I've created/added since then).
Might be better off moving any files you do not use on a regular basis to external storage.