Another way that I like to think about this is that if you think of a stock price as following brownian motion (e.g. follows a random, well defined process), th

Another way that I like to think about this is that if you think of a stock price as following brownian motion (e.g. follows a random, well defined process), then it follows that the stock price has a scaling-invariance property. In other words, the stock prices follows the same process regardless of the time window.. e.g. a day for day traders, milliseconds for HF, or years for long term value holders. Now, brownian motion is just a model for a stock price so YMMV, but still an interesting idea. An investor can pick whatever time horizon interests them and that they're most suitable to take advantage of; e.g. HF traders take advantage of low latencies, technical analysis for day traders, and macro / micro economic analysis for value. As the OP said, there are these three ways to look at this and at the end of the day, all are gambling with different time-horizons and this is possible because of this scale-invariance property.