Think it depends solely on the mind and also on the people who u
'can' interact with. They are actually the ones who 'approve' of
our existence.
Family members or friends, even the girl sitting at the far corner
of your office/classroom whom you have been admiring for quite
sometime, If they don't acknowledge 'you' in the 1st place, don't
even bother about 'you' at all then where is the sense of
belonging? then are you an existence then? Only strong mind through
will make you an existence that exist, weak mind being will make
you feel lost, worthless and needless.
Take for instance even this thread, if no one had reply to you then
is this thread an existence?
I believe there is a vast difference in the 'physically existing'
and 'mentally existing'. U have to make your point more clearer so
people can comprehend on that.
Just my 2 cents worth. 
