Here a few more factors to consider as you research your niche to decide if it is going to be a good one to invest your time and energy into:
How much interest is there worldwide? Is it an event of major impact all over the world or regionally? Is it relevant to some current event that is high on people’s minds for now?
This is the lifespan of that particular hot topic. Maybe, like the Olympics, it’s a high intensity event with a very short duration. In that case, you either need to plan ahead to get out after a bit, or to market much earlier than the actual event, to maximize sales.
Even if the hot spot is short duration, but high intensity, is it possible it is going to evolve into another area of major interest? In that case, you might want to plan ahead for the potential spin-offs in topic themes that can occur.