If by “cracking passwords” you mean reversing password hashes in a database, quantum computers aren’t going to make a big dent there. The standard industry ways of doing that wouldn’t be affected much by QCs. Breaking encryption, OTOH, with QCs is a concern, but also vastly overrated. It would take orders of magnitude more qubits to pull off than what’s been worked on so far, and it may not be feasible to juggle that many qubits in a state of superposition.

I get really annoyed when people focus on breaking encryption with QCs. They are far more interesting and useful than that.

QC can make logistics more efficient. Have you ever seen photos of someone unpacking a giant Amazon box holding one little micro SD card? Amazon isn’t dumb about these things, but our best methods of packing an entire truck is a guess. Packing algorithms would take too long to calculate how to perfectly pack it, so they come up with a solution that seems OK, and that leads to a few “filler” boxes that are unnecessarily large, among other inefficiencies. QC can solve this problem without taking the age of the universe to come up with a solution.

The order in which that truck delivers those packages can also be made more efficient with QC.

Then there’s molecular simulations, which have the promise of making medications that are more effective, more likely to pass trials, and with fewer side effects. This can be done far faster on a QC.