They're a business device.

Historically, if you have a genuine business need for an HSM you're likely to be spending tens of thousands upwards on compliance costs and key management.

The device itself has become such a blip of a line item that it's dropped into the prosumer range.

I think this is partly due to racked HSMs (with a dedicated priesthood to perform the necessary rites) being slowly replaced with KMS and cloud HSMs in many (most?) new applications.

I'm not sure these things (small HSMs) can ever trend down to being true consumer commodities in their current form. The problem is that long-term you WILL lose your data unless you do proper key management, which is not something most people can do for themselves.