Uhh. I passionately don't want mega corporations to have this information about me - European or not. My bank has it, but even then I'd rather they didn't!
If companies can trivially identify people bad at saving...that won't end well.
Intensification of the already powerful psychological warfare waged on regular people to separate them from their money and concentrate it in the hands of those with enough wealth to engage in this kind of psychological warfare.
Why is that a negative outcome (not in the case of scamming)? The advertiser makes a sale, and the customer gets something that they find value in. It's a win win situation.
Sorry but how optionnal is google, really ? Even if you are tech savy enough to use better tools, the rest of the world is still sharing their data with them and so your data too as you interact with it.