What's the incentive to master a game already beaten by AI?
What is the incentive to do any artistic endeavor, if you are not planning on being one of the world's best pianists, or painters, or singers, or furniture-makers?
Go was probably already solved by some distant species on a planet far away. Did that make it any less enjoyable for us to play? What's the difference?
If I do it to make a living, that’s one thing. If I do it to be “the best,” that’s another thing. If I do it for the pleasure of learning to do a thing, that’s a third thing.
It’s the same with games, but the emphasis on winning skews the culture towards wanting to be “the best.” But for those following the third path, AI beating humans changes nothing for them, just as synth bass and sequencing changes nothing for me.
If suddenly computers can create perfect, beautiful music, I will still play an instrument.
I didn't downvote you because I guess it's a fair question to ask, but it is a rather naive one. Why learn arithmetic if a computer can do it?