I am not sure this mentality about "alternative routes" persists once you are out of academia. In other words, this is a narrative academia spreads to avoid brain drain, but it actually backfires, and once people are out, they don't care anymore.

Yes, for sure, once people are out they definitely don't care anymore. I was referring more to the higher levels in academia that still seem convinced that people that leave academia are just not dedicated and competitive enough.