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They always try to get me to punch in my loyalty card when buying (only) tobacco even though you don't get points on the purchase. It's made me wonder what they're doing with that data, and selling it to insurance companies came to mind.

You don't need a loyalty number to track purchases made on the same debit/credit card numbers (though it may improve it slightly).

just use cash for tobacco.

I generally retire loyalty cards after a few months and ask for a new one next time I checkout. I also never fill in the phone number or other information.

But still I generally pay with cc/debit cards so the banks still know where, not necessarily what, but how much I spent.

What benefit is there in retiring loyalty cards? Creating noise to deflect data collection? Optimizing for returns on some financial aspect?