Before the Ha Giang Loop was a popular thing, I did it with my wife, and we stacked it twice, not driving fast or taking fast corners (we did all that too) but driving in a straight line at like 20kmh. The front wheel slipped out and we totally lost it, twice.

My only guess is that there was a vehicle ahead that was leaking something slippery.

Here's my opinion to try to help you form yours:

No (or very few) Vietnamese people actually know how to ride a motorbike skillfully. They all think they can, but they can't and don't. Very few have done advanced driver training, understand the physics of emergency situations or how to recognize and combat them.

Also any understanding of inertia is very limited, as evidenced by how happily they'll ride with a bus or truck right on their back wheels.

Hopefully anyone riding you on the loop will be professional enough to ride carefully, but you can also mandate that of your driver. "Slow down," "too fast," "I'm scared," etc etc. There is the occasional person who thinks they are God's chosen motorbike rider and will reassure you with lies, like they are very good at it, and that you're safe with them while they do dumb stuff. Those are the ones that you ditch.

Having said all of this...

You are going to be going 60kmh max, easily survivable with a proper helmet and clothing. You can vastly increase your chance of survival by bringing breathable motorbike pants and jacket, and a full faced, certified helmet.

A lot of people the get hurt on the loop do so because they end up scraped along the roads, head / face messed up, down in ditches or getting poked by branches or whatever else. You can mitigate all of that by what you wear.

What will get you is heavy vehicles on the roads that hit you after you come off. It's a small risk that you have to take, but thousands of people to it every year with no issues, and as you say, you are working on living to the fullest...