There are two different kinds of randomness [1], one is lack of knowledge, the dice you could calculate or the precise times of keystrokes which could be easily

There are two different kinds of randomness [1], one is lack of knowledge, the dice you could calculate or the precise times of keystrokes which could be easily measured. The other is 'true' randomness, that is the claim that no experiment or calculation could predict the value of the random variable. Bells inequality can (sometimes) distinguish between the two. And it turns out that quantum mechanics allows to measure Bells inequality. The result of these experiments is, that there is no straight forward way to introduce 'hidden' variables such that the randomness would just be a lack of knowledge. And it does so in a way that allows for experimental errors. (Sorry for being quite vague, it is quite late here and it would take some time to remind myself of the details.) So if you want to claim that there is no such thing as true randomness, then you are essentially calling for another revolution of physics on a similar scale as the quantum revolution at the start of the last century. It is entirely possible that this happens, but it contradicts the most fundamental theories of physics we have. [1] Actually three, it is not obvious what optimal strategies have to do with either of the definitions above.