You would think that it's an easy lesson to learn, but for a large segment of society it clearly isn't. Many think that anything said on social media should be free of consequence. Others think that memes don't count as speech. Some don't read, can't grasp, or are just too obstinate to understand what their signing of a contract actually means.
No matter how many cautionary tales we see, there are always going to be a few that don't get it or have to "be real" and will get themselves canned.