I know that in mathematical terms, finding a private key of a bitcoin address is virtually impossible ... but not impossible. Having said that, a site like
https://www.privatekeys.directory/ gives the ability to virtually explore all the private keys existing in the elliptic curve. The Random button on the site
https://www.privatekeys.directory generates pages of private keys that could reveal addresses with a positive balance!!!
Considering that whale accounts and exchange accounts contain thousands of bitcoins, one lucky guy could accidentally find millions of dollars on hand !!
From what I understand the only defense against this event is to divide your assets into many accounts to reduce the risk. But even this trick can't ensure your funds aren't stolen by a lucky dude.
Humans are very bad at reasoning with extremely large numbers, and probabilities.
When you say "not impossible" you make it sound like it's probable because of a limitation of our language. I guess it's easier to understand it if you compare it to something else.
The probability of a human to walk through a wall is also virtually impossible, but not impossible based on quantum tunnelling:
the probability of a human of tunnelling is e^-10^35.
Would you try to walk through walls? of course not. Same with accidentally finding the keys of another person's Bitcoin wallet.