The ATP ranking requires players to play in :-
(1) 4 Grand Slam
(2) 8 World Masters 1000
(3) 7 Other Tournaments
(4) ATP Workd Tour Finals
Can a player defy this and not care about the world rankings, theoretically?
I do understand that these tournaments are also needed to transition into playing styles of different courts but I am asking just theoretically what would be the consequences?