Yes, that's correct. There are many high paying keywords in the health and finance niche. You can use the google sktool to find some of them
Yes it is true. More demand => more online business => High Competition => High CPC => High ad revenue
There is a quote that "Health is Wealth". Nothing but health & money related niches fetch more income on adsense.
Yes you are right. While picking a niche, you should consider the potential players in the niche. In health there are many potential advertisers with high competition. So the CPC of a click can be high.
high cpc ads are health, pharmacy, finance, attorney, legal. Any ads that can fetch a huge return on investment will always pay high.
But it is also highly competetive too. Therefor if you are relaying on organic search traffic then you need hard work and patience. Not a niche for those who wanted 'quick cash''
If you are talking about search traffic I can pretty much assure you its going to be long- at least 6 months of continuous work in order to rank in page one. I had another blog in another competitive niche (mortgage) Took me about 6 months with hundreds of links and countless amount content and stayed in page one for only half a month and eventually overtook by competitor again with more links. Gave up on the blog altogether and focus on a easier fight instead.
Then be ready for a furious war. This niche is highly competitive and many old big players are there. Too tough to achieve a nice SERP.