tldr;
So when it comes to energy saving the things to focus on are the boring tech of lights and kitchen appliances. Especially any sort of heating appliance. Trying to save a few watts on computers won’t make much of a reduction in electricity bills.
While I agree with the overall notion, the water kettle example calculation seems to be extremely wrong. A kettle uses around 1500W, while a gaming PC is around 300W (or more). Thus running a kettle for a few minutes does not equal several days of running the PC at 100% CPU utilisation. Not even close.