My passport is precious to me so I can understand the concern.

Whilst airborne, it sits nicely in my jacket. I often do not give it to FAs to be hung up when traveling internationally there is usually a coat hook on the seat (in C/F). In domestic flights, I either leave it at home or bring it with me. If I do the latter then it goes into my leather passport case, which in turn sits in my bag and stored under my seat.

When I am traveling on land and if I do not need my passport then I have it stored at the Hotel secure lock (front desk usually guides me to their secure safe area). But if I need to have it with me then it is in my jacket or in the case inside my bag.

I've never had my passport stolen. The biggest threat to it is me misplacing it. Hence, I have devised the above plan to minimize the past hassles and headaches. Hope this is of some value to you.