Can a 0.5% reply rate just be...cold emailing is tough?

So I went through all the steps, created multiple domains/inboxes, warmed for months (continue warming), verified and narrowed my list, kept emails to 20 per account per day, tried A/B/C, etc etc.

And after all that, I have had 3 replies after sending 600 emails. I've checked my ongoing mailreach delivery score, and I'm still 98/99 on all mailboxes.

I am targeting a highly competitive industry where people are being hit on their emails and phones all day long. So I'm wondering if it's less about my infrastructure, and more that this is just going to be tough.

I will say, of the 3 replies, 1 turned into a one hour phone call and is a true prospect. Totally worth it. It's just a bit of a bummer seeing such a low reply rate.

As a side note, we're killing it on a parallel LinkedIn outreach with 18% acceptance rate and 7% conversation rate.