If freedom of speech is absolute, how come it's not applied for private spaces and for the Internet?

That’s what it is. You have no right to use other people’s stuff. If people let you use their stuff, they can tell you how you can use it, and they can tell you to stop using it any time they want.

Threats of violence

Revealing classified information

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Fraud

And much, much more.

Insider trading

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False advertising

Perjury

No freedom is absolute.

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Revenge porn

Freedom of speech does not apply to:

Terroristic threats

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If you’re wondering why free speech doesn’t apply to the internet, it’s because you have no right to use other people’s stuff for free.

HIPAA violations

Child pornography

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Conspiracy

Trade secrets

Insurrection

Why do wives cheat on their loyal husbands?

You have freedom of speech. If I loan you my computer, I can tell you not to use it for certain things, because it’s mine, you have no right to use it, and if I give you permission to use it I can tell you what you can and can’t do with it.

You have freedom to travel. If I loan you my car, I can tell you not to take it out of town, because it’s mine, you have no right to use it, and if I give you permission to use it I can tell you what you can and can’t do with it.