3 Week Old Mavic 2 Pro Flew Away seconds after take off

[Meta4]

Not completely unnecessary, or a waste of time. Calibrating the compass can make the flight safer. See the flowing link:

You'd only say that if you don't understand what compass calibration actually does and when it mightbe necessary (almost never).
Yes, recalibrating the compass before each flight is a complete waste of time and not at all necessary.
It cannot make your flight any safer.

I fly where there is hundreds of feet of topographic relief, tall trees and/or buildings. RTH altitude and direction is almost always a necessary part of my flight planning.

Even then, it would be extremely rare that you would want to set the Loss of Signal action to anything but the default of RTH.

The GPS system can be very reliable, but not available all the time for the reasons you mention and others. The follow resources may be of interest:

The GPS outage schedule shows times that a particular US GPS sat might be out of service.
Not how often the whole system is down ( which is never).
It's also only showing information pertaining to the US GPS satellites, with nothing of the other navigational satellite systems that DJI drones use.
Unless you are using an old drone like the old Phantom 3 Standard, your drone accesses many more sats than the US GPS system alone.

 

[Jamesz]

It really is worth learning from the advice of true experts like sar104 and Meta4 about compass/imu function; you will realise that those advising re-calibration before each flight are ignorant of how drones actually work. Checking for local magnetic anomalies (underground steel) and making sure the drones real-world orientation agrees with the display are the keys to preventing fly aways, not performing a ritual without understanding the physics!

 

[Rogat19]

While the OP may be depressed, and that may ease the pain temporarily, it probably isn't a good idea to encourage illegal substance abuse ?

(We know you meant drone of course, lol.)

I would expect nothing less as far as comments go from a South Australian hahaha

 

[MAvic_South_Oz]

I would expect nothing less as far as comments go from a South Australian hahaha

Hey, I don't live at Murray Bridge or 'lizbef' !
(No offence to normal people here that may live in those majestic places.)