Don't forget about luck. It would be 13.2 billion years if in the very last second of that 13.2 billion years and you happened across the correct private key. In reality, you would come across it sometime sooner, right?
No.
In reality, you will never come across it as long as the address was generated from a truly random private key.
13.2 billion years is the time to generate 2
89 bitcoin addresses if you continuously generate 1 billion addresses per second every second without interruption the entire time. There are 2
160 possible addresses.
In reality, you would not find it in the very last second of that 13.2 billion years or any other time in 13.2 billion years. You would have a 0.000000000000000000000285% chance of finding the right key in the first 13.2 billion years. In reality, you would need to continue for multiple billions of universes to even have a 1 in a million shot of stumbling across a working key.
Side thought, what is stopping people from importing random bitcoin private keys at a mass rate.
The money it would cost to run that much computing power, and the futility in wasting all that money with effectively 0% chance of gaining any revenue.
With the growing number of users and addresses used, at some point they would get lucky with that too, right?
No. And they'd get FAR more bitcoins FAR faster by actually mining instead of wasting computing power on such a useless effort.