Is it possible to run out of sperm?
The male body produces roughly 1,000 sperm per second, so no, a
healthy male can never run out of sperm. However he might (through
frequent ejaculation) temporarily not have enough to ejaculate or
to be visible.
It depends on the health of their reproductive organs. It is in
the testicles where sperm is produced. But, if a man is a heavy
drinker and/or smoker, it can damage the sperm and in severe cases,
stop sperm production totally.