I would say the biggest risk of IoT is the lack of secure communications and data storage.
ITNS Consulting posted an article explaining the 5 biggest threats relating to IoT. One of the items listed is communications. In the article, they go on to say how servers or networks communicating multiple IoT devices together is a major risk to security. While the devices may be protected the channels communicated between them are not. This can lead to network attacks or spoofing.
Another concern they listed is the IoT device itself. Sensitivity to the device’s firmware or interfaces can expose to others how to best attack the device itself to get information. This can happen by updates that are not secure and settings that have not been adjusted.
The article citation attached below also goes on to say what companies or people should watch out for, other sources, and more ways IoT can be exploited that were not touched on in my response, and highly encourage others to read it as well.
ITNS Consulting. “Top 5 Threats Internet of Thing (IOT) Devices Pose to Data Protection & Privacy.” ITNS Consulting, 28 Dec. 2022, itnsconsulting.com/top-5-threats-internet-of-thing-iot-devices-pose-to-data-protection-privacy/.