YMMV, but aside from anyone that started in the Google & Facebook area, huge swaths of the economy are still dominated by closed source software. From personal

YMMV, but aside from anyone that started in the Google & Facebook area, huge swaths of the economy are still dominated by closed source software. From personal experience, this covers: any kind of software-driven hardware, health care, tax, CAD, POS, finance, transportation, & retail. They're changing. But I'd estimate most Top 500 companies are at 0-25% open source migration of core business processes.