See what people spend their time and money on. And see what make them emotional (angry, happy, sad, etc). Look for the things that ‘matter’ to them.
Any value that could potentially be monetized can be traced through these signals. it’s not easy, but it’s a good starting point.
One very interesting thought I had recently is that any human behavior has a direct purpose and a ultimate purpose. Ultimate purpose is the same no matter what the behavior is – achieving a goal with the highest efficiency. Let’s say you want to buy a watch, You spend days digging through the web, why? Because you want to purchase it at the lowest price with credibility to the trade. See, you look for the watch because you want to buy it but fundamentally you are trying to achieve something and you want the most efficient way of achieving it so you end up spending a lot of time finding that ‘most efficient path (for example buying the watch from this vendor A at the lowest market price, or maybe he’s willing to give you the watch for free because he’s having a really good day. Either way, we try to achieve the best case scenario)’.
So I call this ‘fundamentalism’ way of thinking, I don’t intend on relating it to any established academic stuff so forgive me for using the term wrongly. But honestly i don’t really care.
So once we get down to this level, we have a more clear view on the society. If your service shortens the process of this pathway-seeking behavior, people are likely to use your service. Now we use that as a starting point to look for a new business idea.