[sniperjoe360]

Odds for a never smoker aren't well estimated, but I'd say it's in the single digits. Definitely less than 5%. It depends on one's radon exposure, asbestos exposure, exposure to gas stoves/coal burners, smog pollution, and genetic background. Many lung cancers in non-smokers are driven by single gene alterations (i.e. EGFR, ALK)

Your second question is also interesting. For a nonsmoker to get to 25% lung cancer risk, I guess he/she would have to live past 80, which few people do.

Your statement that we all probably get cancer eventually is mostly true - as we age there is an accumulation of mutations which eventually should cause cancer. Some super-elderly people in their 90s and 100s may have more senescent cells than others, and paradoxically lower their risk of new cancer later in life.