OP didn't mentioned to slash salaries just by half not by 75%. Most IT people in western countries in Europe are not making even 200k per year. Even in London is hard to get 120k unless you maybe working as a contractor.

A lot of those SV talents are not american but migrated from europe or elsewhere - there are still talented people in EU who just simply don't want to move to USA these days even if salaries are at least 2x. You wouldn't have a problem finding real talent in eastern europe for 150k.