I respect a top 20 Tetris player more than I respect a college graduate since the college graduate just has to convince the teachers to like him and do exactly as he's told compliantly. The Tetris player has to be the best at something difficult and competitive that shows intelligence.
Can hardly blame your son for not taking something seriously which is mostly taken seriously because everybody thinks that everybody else takes it seriously and you can't just opt out of impressing others because it will limit what you can do and earn in the future. College itself is just a glorified game but a far more boring and unfair one than Tetris.
after reading the comments I found another thing that is unexpected but related, he has been trying to write a program beating Tetris since high school, from initial python to AI. He was competitive on math(ranked in top 30 nationally at HMMT at 9th grade), so his missing out tier1 school(e.g. MIT) disappointed me a bit, but it's what it is.
On the other hand I had a MIT PhD colleague who graduated 11 years ago and is a senior software engineer just like the rest of other colleges' graduates. I guess school does not define everything(no offense).
Can hardly blame your son for not taking something seriously which is mostly taken seriously because everybody thinks that everybody else takes it seriously and you can't just opt out of impressing others because it will limit what you can do and earn in the future. College itself is just a glorified game but a far more boring and unfair one than Tetris.