Why Not Share Fountain Pens with Anybody

Fountain pens must not be shared.
It is true that each one has his peculiar way of holding the pen and that the nib gets used to the angle at which it is held.
So it is a good practice not to share one's fountain pen with others.
But refusing to lend your fountain pen would have made you unpopular.
But I would never lend my Mont Blanc or Parker to any one. I never had to. These expensive pens are usually not carried in one's pocket. They are usually for private and limited use and kept safely in one's drawers in the desk. It was too risky to carry it around. Chances were you would lose it. I have lost several "Heroes" in my lifetime.
I have met people with extraordinarily neat handwriting who used very expensive pens and who flatly and without fear of unpopularity refused to lend them to others. But I wonder if they thought of mundane mechanical and geometrical factors like wear and tear or the angle of the nib etc. It was more due to the desire to have exclusive rights to something they were proud to possess and were fanatically attached to.
It's like never wanting another person to drive your Mercedes car.
Any way there are no hard and fast rules about this.
But I agree that it is wise not to share one's expensive pen with others.
To avoid embarrassment, it is practical to keep handy an inexpensive ball point pen also and lend it on occasion.
Refusing to lend your expensive fountain pen may lead to some unpleasantness, particularly when the borrower does not know it is expensive, and does not know why a pen deserves a single owner.
In a public place, when someone wants to borrow your pen, lend it but take the precaution of unscrewing the cap and keep the cap with you. Chances are he will be less likely to sneak away with your pen. Without a cap a fountain pen cannot be kept in one's pocket without soiling the shirt. The man is more likely to look around for you in the crowd and return this "half object" which has just served his immediate purpose.
Fountain pens went out of fashion in America and nowadays even I have almost stopped using them. Ball point pens were horrible in the early days and we were not allowed to use them in schools. It was claimed that they spoil our handwriting. But over the years there have been great improvements in design and nowadays, for sheer convenience, it can't be beat.
I still prefer a fountain pen when I need to write a whole page or two.
But nowadays I type more than I write.
All writing is limited to a quick jotting down of info in my scribbling pad or signing on forms.
For this a ball point pen is definitely more convenient.