Question: Why not buy one of those hearing devices from the drugstore rather than a more costly hearing aid?
Answer: The devices in the drug stores are not hearing aids. They are not set for the frequencies or pitches needed for your hearing loss in order to bring in only the sounds that are needed.
These devices are amplifiers that turn up most all sound. They are very basic with non-linear circuits containing minimal electronics. There is no guidance for severity of hearing loss or supportive services that may supplement the amplifying devices.
The success of hearing aid use lies not only in the product, but also in the ability of an audiologist to program a device for your own lifestyle, modify its abilities, and ensure follow-up care so it serves you well for a long time.