I don't believe in the strong form of the efficient market hypothesis. (I agree with some weaker versions of it).

If all humans made all investing decisions from a perfectly rational state, then the efficient market hypothesis would probably hold true, but in reality people sometimes become either overly confident or overly fearful, creating opportunities to exploit them by being more rational.

That said, in order to beat the market you must be better than the average participant (which is a high bar), and you must be enough better that you overcome trading fees. This is similar to playing poker, you must be significantly better than the average of the other players at the table in order to beat both them and the rake.

For the average person, the advice to simply buy index funds with a portion of every paycheck is the advice that will bring them the most utility, and one could be considered to be doing them a service by convincing them that the efficient market hypothesis was true, even if it isn't.