There are many reasons but all belong to the categories of self-interested and altruistic. Let's start with self-interest. First, the act of writing lends clarity and coherence to one's thoughts as it forces you to think over what you are doing. This is something we have come to realize even more strongly since we started this service. We have consistently strived to trade in an orderly, clear and disciplined manner. Articulating and putting down our rules, printing out charts, and commenting on patterns for the next day has made us into more focussed traders. In a way, parts of it are like an enhanced trading journal (which, by the way, we recommend to all).
We decided to charge just so much as to be motivated to keep doing such a service (if it were for free we are sure we would not feel pressured enough to update it on a daily basis) but not so much that it becomes too expensive for traders who are starting out, or for people who subscribe to multiple services who do not want to add another $150 a month to their bills. $30 a pop sounded just right. Having it so inexpensive also means that trading will always be the main source of income for us, since as soon as you stop trading and become an observer, you lose the trader's edge: that instinct of looking at a stock's price action and seeing it set up even before the pattern has emerged on the daily chart.
As for the altruistic reasons there is only one -- we were helped by others when we started; now it's our turn to give back.
