Bitcoin wallets are protected by 256bit encryption meaning there are 2^256 different private key combinations.
Now, With fastest supercomputer power, it will take approx. 1.5 billion years to crack it...
Good News
According to Moore's law computers are getting faster exponentially every year, so if we assume that the computer speed doubles every year, then after 59 years it will take 1.13 year to crack your BTC wallet.
So tell your friend to wait for 59 years....
Maybe he can write it in his will for his grandchildren's so they can try cracking it...:)
That would mean that it would take 1.13 years for anyone to crack anyone's, breaking bitcoin entirely