Doing research elsewhere regarding fly-aways (specifically DJI products), ... not setting the HOME position are major concerns (if not the cause) of many fly-aways
Although you will often see people asking if a pilot set the home point before taking off, this really isn't the issue people imagine.
Your Phantom will automatically record a home point as soon as it gets GPS reception.
Normally that will be a short time after you start things up and before you launch anyway.
If you were very impatient and launched early, your Phantom would still record a home point as soon as it gets GPS reception and that would probably be within 100 metres so it wouldn't make much difference.
As part of the before flight check list I have what to do in the event of a fly-away. The assumption is no matter the cause this is a true inflight emergency and can cause personal injury and property damage. For these reasons I have have including intentional ditching the aircraft while it's still in sight. In laymans terms the aircraft is expendable against the unknown results of its loss.
If your Phantom was really flying away, and not responding to your control inputs, you would probably have no way to get it to do anything anyway.
But I think you've picked up a false idea of "flyaways".
The whole concept of a flyaway came about in the early days of drones.
An owner that lost their Phantom without understanding the cause of the incident would say that their Phantom flew away and it was accepted by most people.
But since the Phantom 3 and DJI Go app, we have recorded flight data that allows us to investigate incidents and find out what actually happened.
This has shown that there are quite uncommon genuine hardware malfunctions but the overwhelming majority of lost Phantom incidents are due to operator issues.
Being able to see what causes such incidents also helps everyone to be a better pilot because we know what can cause problems and how to prevent such issues or how to manage them.
I would go so far as to say that there's no such thing as a flyaway.