See this has a lot of different answers. Some of which are simple and others which are a bit more complex.
Also, with this post being a "the hobby" post rather than a "my hobby" post I have to lean on more general reasons.
Let's take this for a walk.
Tabletop Games are a social hobby. They are played face to face with other people around a table.
That interaction and social experience is key to the hobby as a whole as it helps to demonstrate the benefits of the games and not least of all remind everyone that the games are a lot of fun. After all they are games!
Tabletop Games are also a fantastic family past time. Non-competitive games in particular are great for families to play together but the hobby aspect of competitive games can be very strong activities for families to participate in together, in particular when it comes to War Games where the miniatures require painting.
All in all the hobby of tabletop games is about sitting down with likeminded people and having fun playing those games. It's also not necessarily always friends as in some environments it can be commonplace to play with strangers too; strangers who may in time become friends.
Clubs, stores and conventions all give people the opportunity to participate in the hobby with friends and strangers alike which adds to the social and community elements of the hobby.
So why play Tabletop Games? To have fun whether that's with friends or with complete strangers sharing the hobby together in a social situation.