Over the past few months, I've found that there are 3 main reasons people like (or, more broadly, "star") anything on social networks:
This is not to say there aren't other reasons but just that these are the most common ones. Unsurprisingly, liking something usually (for most people) has nothing to do with actually liking it in the physiological sense of the word. Of course, you'll hear a different story if you were to ask most people why they liked something. And, to be fair, they're not lying (not consciously, anyway). That's the beauty of confabulations.
Likes are one of the most physical manifestations of signalling of our time, and they come with the added benefits of being fast and cheap (not always, though, but let's save that for a deeper dive). But what really interests us about likes, whether we admit it or not, is that, true to their signalling roots, they are monetizable, both, for cash and in kind.
What's not to like.