Comment by cortesoft

I feel like Lindy's law doesn't work for things whose observation is partly controlled by the thing itself.

For example, take something like a fad or trend; they don't have a hard end date like human lifespan, so it should follow Lindy's law.

However, the likelihood, on average across the population, that you observe a trend is going to be higher at the end of a trend lifecycle than at the beginning. This is baked into the definition - more and more people hear about a trend over time, so the largest quantity of observers will be at the end of the lifecycle, when the popularity reaches its peak.

In other words, if you are a random person, finding out about a trend likely means it is near the end rather than the middle.