You are right in your understanding of CPC :imho:
CPC has to do with advertisers' budget. Therefore ads related to banking and insurance products, novelty tech items, medical cures, luxury products, special education offers etc. usually pay higher per click compared to other keywords.
High CPC does not mean high search volume of course, sometimes in rare cases it doesn't imply a high competition at all. So what makes money is traffic, most of the time (if not all the time). You can buy domains with existing backlinks or type-in traffic such as typos to monetize them by domain parking. Alternatively, you can take the longer but enjoyable path of website developing. If your keywords have good search volume, plus fair CPC values, you have a chance to earn money if you can make your site appear at first Google results page. Still you will have to visually improve your web site, and find ways to make people click your ads. That's been the hardest part for me so far. They just don't click! Lol. I usually combine affiliate ads such as Amazon with contextual ad mechanisms such as Adsense, still I have to add lots of magic (original information, high visuality, entertainment, etc.) to my sites to attract people.
Hope to be a bit helpul to you,
Regards / Dorian.
