Ask HN: What markets should be disrupted?

I found several sources for Markets ready for disruption, like education, health, insurance, etc.

But what is the best way to look for special ideas that should create a significant impact?

Some sources:

https://www.linkedin.com/pulse/20140709144459-8336796-32-markets-ready-for-disruption

https://www.quora.com/What-are-some-10B+-markets-ripe-for-disruption