Except Coinbase isn't free - you are paying with your data.

As with everything online, if you are getting something - anything - for free, then you are the product. Why do Coinbase want to entice you to sign up for their site with such "Learn and earn" promotions? Because before you can access these promotions, you must first hand over all your personal details and scans of your documents. And then at a minimum they have your name, address, email, phone number, bank details, and the fact that you are interested in crypto. That information can be endlessly monetized by selling to third party advertisers, marketing agencies, governments, and more. Data brokers will buy that information and link it to your social media profiles and other online presence and again resell that to anyone who is interested. If you actually withdraw any coins you earn with them, then now they know some of your addresses as well, and their in-house blockchain analysis company will start working on linking as many different addresses to you as possible. Every extra data point they can gather makes their profile on you more valuable to third parties, and so they can make more profit from endlessly reselling your information.

If you think having your data splashed around dozens of companies and accessible by thousands of individuals to use in any way they like is worth it for a few bucks of some shitcoin, then go ahead. Otherwise, you'll get a better return for your time (without the complete loss of privacy) by working a job and then using the money you earn to buy some bitcoin.