I agree with you, even if the giveaway is high, is just a terrible idea to give our information to those businesses. I don't think they would sell it, but no one know when they could get hacked.
i dont think that their give away is high because a giveaway usually means little to less . but its okay and you must not worry alot to give your information because its obvious that blockchain.com is 100 percent legit and trusted for a long time up until today . not unless you will get a phishing email or invitation , that simply means it is your own fault and not blockchain if ever something bad happend to your account and info .
Also it has nothing to do with email spoofing because that message appears on blockchain.info's website and mobile app.
using it solely as a wallet then it doesn't really need at all and also $25 in exchange with your identity isn't really a good deal.It wont really be fair on the first place.