It's not just the fun hacking stuff like locking up iPhones and other Bluetooth devices, popping the charge port of teslas open, using BadUSB to deploy payloads, brute forcing electric barriers in parking garages, changing the TV channel in a waiting room or pub,

It can be used for storage. It's a digital swiss army knife. You can learn all about signals and wireless technology protocols by using it.

There are tons of legit usecases, reading animal RFID chips, saving hotel and work access keycards, IR scanning (e.g. can find a disconnected from WiFi robot vacuum or search airbnb for IR devices), programming RFID chips, backing up keycards and apartment badges, backing up Nintendo amiibo, universal remotes, bluetooth speaker remotes, using BadUSB to deploy scripts to onboard work computers instead of carrying around USB drives, opening your garage door, SPI, UART, I2C to USB converter, using it as a flashing and debugging tool, using it as a fuzzing tool to test protocols and signals, scanning networks (then analyzing the packets with Wireshark to see your password for example), pentesting IOT devices, etc. etc.