Would Microsoft not exist without open source project? Microsoft is that company founded in 1975, but the GPL license only appeared in 1989, and BSD licenses appearing at roughly the same time just because of the Unix Wars.
Big tech companies can easily hire manpower to make proprietary versions of software, or just pay licensing fees for other proprietary software. They don’t rely on open source. Microsoft bought 86-DOS to produce MS-DOS; Microsoft paid the Unix license to produce Xenix; and when Microsoft hired former DEC people to make NT, it later paid DEC.
Instead, modern startups wouldn’t exist without open source.
Indeed, open source exists despite Microsoft trying its hardest to kill it. Microsoft was (and still is) a ruthless, savage competitor. Their image has softened as of late but I'll never forget the BS they did under Bill Gates and Steve Ballmer.
Microsoft wouldn't exist without the theft of CPU time on time-shared computers.