** The Magnus Effect makes my head spin in a way that feels good.

** Learning to create spin.
** Learning how to contact and touch the ball for different effects.
** Learning to compensate for incoming spin by where and how you touch the ball.
** How it feels when you contact the ball in a way that causes the ball to sink into the sponge and stretch and distort the topsheet without bottoming out, and how that creates massive amounts of spin with minimal effort.
** Always needing to watch, observe, pay attention and respond to what your opponent does to the ball.
** How, when you touch the ball a certain way, at a certain angle, you can make the ball dance.
** Seeing the float or arc of a ball fizzing with spin from that just so....precise contact.
** Seeing how, as you develop skills, your brain starts reading spin, seeing the axis of spin (point of least spin sensitivity on an incoming ball), seeing the equator of the incoming spin, (point of ball where spin will feel the strongest), and how all this happens intuitively without you even consciously realizing it is happening.
** As your skills at reading spin increase, how you start seeing how many different ways you can counter that incoming spin, whether contacting the point of strongest spin or the axis of spin where the spin will have the least effect on your shot....right now I am thinking of how traditional penholders use the traditional penhold BH to do all kinds of neat and crazy things with spin just by pushing forward with the racket at a certain angle, evil things that can be done to a ball just by giving back the incoming spin, or how you can respin, how ZJK would do on all his over the table BH loops....the massive amount of spin he created from a precise and delicate touch with a fast accelerating racket.
Now, I could keep going on. All of what I have said is related to the development of physical skills, touch, feel, brain processing and spin. I could make hundreds more bullet points on that subject.
Or, as Yoass and Morty have already said quite eloquently, because TT makes me happy.
For me, TT is a beneficial addiction. I can get absorbed in so many aspects of why I love TT. But in the end, when you find yourself daydreaming about something while you are doing something else, when you can't wait to play, those are the signs of why so many of us love TT. And I am not sure it needs any real explanation. Brain fever says it all....doing the St Vitas Dance of Love for TT.....receiving that ecstatic feeling that Dionysus gave the Satyrs and Maenads by spinning the hell out of a ball.