A high CPC means competitors, each measuring their own conversions, have concluded the query is worth paying for. That is a far better signal of commercial intent than search volume, which counts curiosity and buying appetite identically. A keyword with 200 searches at a 45 CPC will usually outproduce one with 20,000 searches at 0.15.
Do not treat it as equivalence. Paid clicks sit above the fold and attract the impatient; organic clicks attract the researcher, and the two convert differently. Use CPC to prioritise and to express organic value in a language finance already understands, not to claim that ranking saves you exactly that amount.