The point of my post is not to scare and say that private keys are not secure anymore No! but to say that theoretically its not fully impossible to generate a key that did indeed existed.
Here is a post I made a while ago comparing the likelihood or various pieces of security we all take for granted:
It is impossible to have a security system which is impossible to hack, and as far as security systems go, bitcoin's is pretty darn good.
Given that most 2FA codes are 6 digits long, there is a 1 in 106 chance of someone guessing your 2FA code.
Assuming an average house lock has 8 tumblers, and each tumbler can adopt one of 10 positions, then there is a 1 in 108 chance that someone will be able to guess your exact house key shape and unlock your door.
Given a standard credit card has a 15 or 16 digit number on it, there is at most a 1 in 1016 chance that someone will be able to guess your credit card number.
If you use a password manager to generate a long and totally random 16 character password, drawing from the full ASCII 95 character set of upper and lowercase letters, numbers, and symbols, (e.g. CY\u4"=t{rV%;N9S), there is a 1 in 4.4*1031 chance of someone guessing it.
The chance of someone guessing your private key is 1 in 1.158*1077.
The chance of someone correctly guessing your password, your 2FA code, your credit card number, and the key to your house simultaneously is 4.4*1061, which is still around 2 thousand trillion times more likely than them guessing your private key.
If you are worried about someone guessing your private key, then you should be absolutely petrified of the security of everything else in your life. For every possible 16 digit credit card number, there are approximately 10 trillion trillion trillion trillion trillion possible bitcoin private keys.