You cant predict the outcome of race even if you already win by huge margin, the unpredictable things will happened like the other racers spun out or having accident which causes yellow flag to make all racers slow down until the accident cleared out, this will give other racers to narrow the margin to keep up with others.
Even the worst racers can gain some points by luck if many ot them are having troubles/issues during races (its incredibly rare but it also happened too)