I believe it is a way of thinking. I once told someone who asked me about the same question "How can you
not see new ideas here?"
I'm a problem solver, and when there is a problem from "keys locked in the car" to "too expensive to move mass to lunar orbit" I just start speculating solutions. Knowing that any problem is in fact a series of problems the other problems get solution speculations on their own, and out of those hundreds or thousands of ideas pop out things that occasionally are both implementable and monetizable.
To give an example of how I think, one day when I was taking a shower I recognized that I'm so busy thinking about things that I sometimes lose track of whether or not I've done one round of shampoo or two. So that suggested a solution where I could make a note after the first shampoo and after the second. And then looking what I had to work with I realized that I could algorithmically determine the issue if I left the cap open on the first go round and if I grabbed the shampoo and the cap was open it was round 2 so just close it. Basically transferring the 'state' of how many times I'd gone around the loop in the state of the cap. Problem solved, no cost. Maybe a nice thank you if I sent it in to "Helpful Hints from Heloise."
So looking around at problems they come in some common forms.
They are the result of something being too complicated thus requiring either specialists or training time.
They are the result of not managing state (like my shampoo problem) where the stage of the solution needs to be recoverable.
They are a result of an economic barrier, so its too expensive to do X which causes problem Y, can you do X more cheaply?
They are the side effect of a desirable thing, so doing X is desirable but has (or sometimes has) undesirable side effect Y. Here the solution makes X better because you find a way to mitigate Y.
They are problems of comprehension. The human brain has a finite capacity for maintaining state, so solutions that either abstract out chunks (and free up the brain for more relevant state) or eliminate complexity, win in those situations.
Then there are solutions that are not currently possible, but would be if 'X' existed. For example, if you had unlimited energy you could easily create liquid fuels out of the air. Sometimes its useful to think about those kinds of things and watch for the 'unlimited energy' appearing in the news (as it would if we suddenly mastered the fusion cycle for example). A variation on this I was doing back in the 80's as a network programmer at Sun wondering what sort of things would be possible when everyone had high speed network access. Consider the more probable new capability like 'easy access to space'. So there are folks like Virgin Galactic, SpaceX, etc who are working toward making access to space available to non-NASA types. What problems are those people going to have? Gucci barf bags anyone? How about the sex market for them? We know that nearly every nerd who goes into space, if they have a wee bit of privacy is going to be thinking how they try out sex in space. What do they need to do that? Bigelow wants to put inflatable hotels up there, what kind of luggage do they need?
And there are all sorts of geeky technical problems like "how do you make white space spectrum available to everyone? ", "What sort of cash drawer thing is useful for an NFC enabled world?", "How do I enable non-technical people to have all their purchased video available at their TV?" (clearly the media PC hasn't quite gotten the recipe right there).
If the market is small ask what folks with high levels of disposable income might want.
If cars can self drive how would you build a parking structure for them?
How can I build something that would auto-plug in my Tesla and save it from being bricked without thinking about it?
What does 3D printing mean for the toy business? Can you build a device which parents of young kids or day care centers could use to generate a steady stream of safe toys?
What would it take to make a solar powered device which recycles plastic bottles or cans into something which is more easily processed into new products? Can you build a device which powderizes these materials and then feeds them into feed hoppers for an industrial scale 3D printer? Bottles in one side, park benches out the other?
The thought sequence, venture wise, is always the same:
1) How many people have this problem.
2) How many other ways are there to solve it or live with it.
3) What would it cost to offer a solution?
4) How does the cost compare with the pain of the problem, and the cost of other options (including 'doing nothing'!)
You can use personal experience to work out some intangibles (like how many lines of code would it take and how long to write) and sometimes you have to construct small experiments which help inform the outcome. The key is that if you are ready to accept that your idea isn't feasible (productwise) to just move on. There are lots and lots and lots of ideas out there.