One question on this subject, answered from our own work, with the numbers.
For fun, above all. Dubit asked US parents and young people, in their own words, why they or their child like to play video games. Fun and entertainment came up in 57% of answers and social connection in 29%. Challenge, creativity and learning came third, on 22%, from a weighted base of 288. Answers could name several reasons, so the shares overlap.