Hi Michael,
Thanks for having the courage to share your story.
Really sorry to hear what happened to you. 24 years ago, I broke my spine in a snowboarding accident and was very lucky to be able to walk again.
Your are absolutely correct that it's always preferable to kite with someone and have someone help you launch and land your kite. However, landing or launching your kite with the help of someone else is not always possible.
If I may give some advice to prevent this situation from happening, it would simply be to activate your chicken loop quick release or to unhook from your chicken loop prior to attempting any form of self-landing, especially in super windy / gusty / stormy days.
Unfortunately, almost every kitesurfer I see self-landing do this while still being hooked into their chicken loop, which means there is no plan B in case the self-landing fails.
Regardless of anyone's skill level, everyone can fail to self-land.
The video below shows how we teach an emergency self-landing to complete beginners in their very first lesson. I believe that this technique should be used in very heavy wind conditions regardless of anyone's experience. When I self-land in winds above 25 knots, I will always use this technique myself which has the lowest amount of risk.
The video below shows how we teach advanced self-landing to more experienced kitesurfers. Note that this technique also makes use of the safety system in case something goes wrong.
Hope this helps.
Christian - KiteBud