For me, it was inability to afford any other toys, so LEGO became my dream medium.
For others, that might be an exciting challenge posed. For example, during COVID we have been doing weekly “LEGO Masters” challenges with my niece and nephews over Zoom, where we pick a theme and then present to each other a week later. They are 5, 5, and 8, and then my partner’s brother, cousin, and I routinely join in. It’s not as much a competition as it is a creativity prompt, an encouragement of presentation and sharing (and thinking about your share of the presentation time), and a way to get to know each other better while distant.
Incidentally, I got into Rebrickable a few months ago after starting to (finally) organize my collection during lockdown and these challenges. I spent a couple hours checking off nearly all of the sets that I know that I own, and when I was done, the site told me the value was about $25,000. I’m kind of shocked.