That's not a reasonable thing to say. "Giving chemotherapy" is almost as general as saying "giving medicine". A young dog with a treatable cancer is not going to cost anything near $10k and should get many good years of life. Some cancers (eg, mast cell) have glorified Benadryl as "chemo".

Just put in the effort to find a good vet, build a relationship, and trust them give you good advice.

I'm not saying this to you, but this has been a terrible post on HN to read, the worst of the community is on display. Lots of confidently wrong people that are very quick to see the worst in others.