Should we hire AI specialists or train our existing team to work with AI?

Our firm wants to expand AI usage across our audit and advisory practices but we have no internal AI expertise. HR is suggesting we hire an "AI Lead" but the salaries I'm seeing seem inflated and I'm not sure what that role would own. Our alternative is investing in training our best senior consultants. What have comparable firms found to be the better investment — new specialist hires or upskilling existing talent?