Let’s say you wanted to meet every person in the world before you died, and it took you 1 second to shake a person’s hand. It would take you 76,415 days solid handshaking time – over 209 years.
That’s clearly impossible, given current life expectancy in the US, 77.8 years. But how many people could you meet in that period of time?
Since we’re assuming a 1-second handshake, the answer’s equal to the number of seconds you’re conscious. Let’s say you sleep 6 hours a day, and start when you’re 3 years old – in pre-school. You’d spend 27,320 days (including leap years) shaking hands, and you’d meet 1,770,336,000 people before you croaked.
But 1 second isn’t really long enough to get to know someone. So how many people could you speed-date in an average lifetime? Wikipedia says speed dating lasts between 3-8 minutes. At 3 minutes per person you’d speed-date a total of 9,835,200 people before you died. That’s about 0.3% of the current estimated population of the US.
Speed-dating the entire world would take you 13,754,634 days – about 37,683 years.
All of this basically to say that even though you do continue meeting new people throughout your life, you’ll still only ever meet an extremely tiny fraction of your fellow human beings, let alone know what their lives are like.