Very coherent piece on a familiar concept.

I think of spikes as ways to sustain streams. They're also the quick route to making bad decisions. It's encouraging to see your investments jump in value every now and then, but if you sell a stock that's doing badly when you could have waited until it bounced back, you're making a bad decision. Another instance: you're steadily learning machine learning, and the motivation starts to drop; you post your little project on HN, and it makes the front page for a day; you suddenly feel better about learning it. In this case, the spike is a sneak peek into the future: you'll have a decent following if you really push yourself to learn.