Right place at the wrong time, mainly.
The Istanbul protests were the exception, as I knew several people and wanted to see the situation personally.
What is true is that Life Goes On. Even in Istanbul or Paris with the huge protests, if you're not in that specific part of town at that specific moment, you wouldn't even know it was happening.
Hotels in HK are wildly cheap at the moment.. it's the time to visit a tourist free city and witness (for better or for worse) history in motion
I agree that it's an excellent time to visit Hong Kong if you do not mind the risk of travel disruption (airport delays or trouble getting around on public transit). This is not a violent society even now, and travelers are not at risk in my opinion.
Why have you experienced so many different riots? Are you a reporter, a protestor or something else?