It really isn't on average. An individual dataset is usually cheap - or are you saying there is a mispricing?
I'd be curious to see how the price compares when selling 10k individuals' data versus aggregate data the 10k people. Presumably if it was cheaper to buy all the individual data I would do that and aggregate it myself.
Private investigators, three letter agencies, and any company wanting to send mailers to my new address when I move all need the individual data to target me specifically.
I totally agree the aggregate data is given more value in a commercial market heavily focused on advertising and now training LLMs, my only point was that there are markets that highly value individual data as well.
I think the point stands that it wouldn't be easy to sell your individual data, and even if you could, it would be for a pittance from someone who is looking to build a large dataset. They certainly wouldn't be giving you an amount that justifies advice like "hold on to your data".