Here's something I wrote on a different discussion about hiring:
Imagine I cost my company $50 an hour in salary, and earn them $150 an hour (revenue of 3-5x salary is ballpark for most companies, we'll go for the low end for some perspective). As a senior dev, I have to sit in all the interviews of people potentially joining my team. Imagine we have 10 people that make it through the HR round. I have to participate in 10 interviews, and then likely 3 more for the final round.
My cost for round 2 is: 10 people x 2 hours x (150 lost revenue + 50 salary paid) = $4k
My cost for round 3 is: 3 x 8 x (150 + 50) = $4.8k
My company has already dropped $8.8k on my involvement solely in the interview room for your typical entry level position. This doesn't even include my involvement in onboarding, training, pre-interview prep, post-interview review, etc. This is also JUST ME, and a very lowball figure at that. Now factor in the cost of the HR round, recruiters, background checks, the other devs in the interviews with me, etc. It adds up very, very quickly.
The "costs of doing business" can easily be reduced by not interviewing for shits and giggles.