If you search the HN archives, I think you'll see the success rate is low but the general feeling is that it's enough to justify the effort people are putting in.

Personally, I don't mind the occasional cold email and will reply politely if I'm not interested.

What bothers me A LOT is the automated emails and automated retries every few days with templated emails trying to appear like they were written by some CEO pretending to be my friend. When that happens, the company is leaving a long lasting bad impression.