Technology boosts productivity > rise of GDP > stock markets on long term, adjusted to this fact.
So on long term, stock markets are leading by a FACT, they cannot ignore (1).
On short term to mid term, stock markets behave chaotic and unpredictable by the speculation of market actors that try to predict the future on a short term to mid term basis. Their speculation contains exaggerations on up or down direction because it’s not based on a fact like on (1) – above.
The speculation acts in an unpredictable way because it is very sensitive and changing very easy direction and intensity because it is based on estimates (and not fact) of thousand of market actors.
So if you are not long term on stock market and instead, you are mid term and especially short term, your investing or trading is almost like gambling. In gambling the whole situation is unpredictable and in a such situation you cannot win. If you win, it will be just luck, and if you believe that you won by your capabilities, it will destroy you on the long term, just like a player of a casino, that won 2 or 3 times and thought that he is very capable and can become rich ; he kept playing, he lost his previous gains and eventually, lost also his capital.
So be a clever investor, be a HERETIC INVESTOR.