There is actually another program similar available (running like a pool) they already have found around 15 addresses since 2016.

Pickwallet is more a solo base program able to find private keys from Bitcoin P2PKH address starting with 1 both from (compressed and uncompressed pubkey) starting with 5, K or L.

So for each run the program generates a random ECDSA key, then create the associated Bitcoin compressed and uncompressed pubkey (so two keys in one run), next will checked those two keys against a list of around 10 million Bitcoin addresses with at least 0.001 BTC balance. In the case of having a match, the program will generate the private key(because you now hold both public and private ECDSA keys) of the Bitcoin address carrying a balance. The program will stop and store the BTC address and private key in your Pickwallet database, and the funds in question would become accessible.

So this is not really impossible(15 addresses found so far just turn the impossible to possible), also depend on the Hashing power you make available to the program. You can check billions of keys per month with a regular quad core computer running four threads.

And again: This software is for educational purposes only!