Let’s face it, the world is simultaneously a big and small place. Humanity progresses in fits and starts based on the singular (and intermittent) intersection of genius and opportunity throughout history. The rest of us are simply genetic stock, monkeys at the typewriter of evolution. It’s an infinitely (to current reasoning) complex random number generator tested against a given environment.
Why then have an online diary? You don’t have the luxury of the evening news and tabloids covering your life, but you’re a person with an unique collection of experiences that should be logged for better understanding of the human condition. If you live and die and no one knows you existed, here at least you would be a data point in the history of humanity.