Any fast FPS shooter (CS, competitive TF2, COD and others), any RTS (LoL, Dota 2) to start with, if you're a bit older - MMORPG is essentially grind for 10 hours or pay someone else to boost you.
Quite the variety, most of which Ive also experienced.
But your original claim simply doesnt apply to most of these (MMORPGs are exception). What I suspect is that the barrier for reaching "flow" or analogous competitive states has gotten too high for _you_ for whatever reason.
In face of this you've constructed an absurd reality to justify your feelings where its the children with infinite time mucking it up.
The truth is, many adults still tap into the competitive spirit in spite of the barriers youve folded to, which I do agree exist, but always have.
While I appreciate you leaving the value of competitiveness in the air... on the other hand, by defining it so purely, you've essentially resigned yourself from participating.
I'm curious what games have molded this perspective.