why, oh why, oh why am i being told to calibrate the compass all the time?
when i get to 'my flying area' i set up my drone, do the calibrating shuffle, place the mp on the ground (a soccer playing field incidentally) and before i even start the props for takeoff, its there again.......compass needs calibrating!!? wtf! ive been nowhere since last calibration. HELP PLEASE!! before i go insane.

You need to go out in the country, away from civilization and try a compass calibration.  That way, you are sure there's no buried ferrous metals that might affect your calibration.  Once you calibrate it in a clean area, you should not recalibrate it  unless there is an accident or other incident that might make your compass inaccurate.  Also, be sure you have no ferrous metal on your body or nearby when you do your calibration.

Hi ! My first  thought. Invest 10$ and change the compass, DIY. See Youtube videos.

Micato Posted at 1-9 11:51
Hi ! My first  thought. Invest 10$ and change the compass, DIY. See Youtube videos.

I think that the second compass is in GPS board which is 50$. That is my second thought.

Hi. I am sorry for the trouble this has caused. With regards to this concern. Did the drone experienced any hard landing or crash. I would recommend to please calibrate your compass outside with strong GPS and less interference to isolate the issue. Please keep us posted for further assistance. Thank you.

Are you flying in low light by any chance

From the 0.400 release notes

"Added requirement for compass calibration before takeoff when the environment light is not sufficient and the compass experiences interference."

Assuming you are properly** calibrating Mavic Pro's compasses correctly, there is possibility your drone has gotten magnetized and needs to be  degaussed.

Problem I ran into when I first got my Mavic Pro P was iOS versions of GO-4 App had a bug resulting in repeated (aka needless) compass calibrations on first flight of day.  Sometimes occurring after a fresh battery was installed for another follow on flight.  For me, problem went away when I switched to CrystalSky running Android version of GO-4 App.

** Make sure you have no ferrous metal, especially magnets on you while calibrating MPP's compasses.
** Avoid having a Smartdevice, Android phone/tablet or Apple iPhone/iPad on you or near MPP during compass calibration.
** Calibrate compass at least 10-meters away from any source of magnetic field interference, buildings, fencing, over-head power, buried metal pipe or power lines, bicycles, cars, etc.

Did mine once when i brought it ,(dinning room table) never had to touch it since , strange some have this issue..