Great question Jack!
We don’t have much data on the tractability of convincing mid-career professionals to switch into EA careers (though we’d be excited to see any evidence supporting or contradicting this if it exists). Our main reason for targeting mid-career professionals over promising high-schoolers is that we think the information value of doing so is higher. This group possesses a lot of relevant skills and has typically been quite neglected by EA outreach, so we’re excited to test out this approach. If we found that drawing experienced professionals into EA career paths was very tractable, we could envisage running similar programmes in the future to fill many other skill gaps.
I do agree that week-long retreats engaging promising high-schoolers seem really valuable though. There’s quite a few programmes like this already (eg. SPARC, ESPR and Leaf ) and Open Philanthropy is excited to fund more such projects if others are interested in pursuing this!