could a thief or witch of light technically change or take the probability of something happening, technically making them able to make anything happen? what if a thief of light carried around, say, a coin or something they could drop, and if they wanted something to happen, they could "steal" the probability of it hitting the floor or some similar definite thing? like is it just me or is light... kind of op

We actually see this- Not in the last example, but I mean. Vriska as the Thief of Light doesn’t change the probability of things happen, but it makes her SO incredibly lucky that things go her way. Terezi’s coin flip would never land on a position that didn’t favor Vriska, her dice can be almost willed to roll the best outcome to do the Ancestral Awakening. Now though, something like the bag hitting the floor, it would likely not change something based around the laws of /physics/ themselves, it seems to me that, chance would make it so that the Thief or Witch could not actually /drop/ the coin in the first place, thus making it not hit the floor.