Every country already has a special government agency that deals with keeping stuff protected. In fact you tend to think the people who know most about this are in government, don't you?
And it's not like there haven't been vulnerabilities found in proprietary software, despite them paying people to keep things safe.
Crowdstrike is a recent example that comes to mind. I don't see how paying for CrowdStrike made it more secure or reliable.
I would also argue that you could take all the $$ paying for proprietary software and contribute it to people who are making the open source software, making the reliance on "free" eyeballs less of an issue.
And it's not like there haven't been vulnerabilities found in proprietary software, despite them paying people to keep things safe.