Approximately 0%. I don't know of any entities that trade as a nonprofit. The point is that if you find something the market needs, you will have inherently discovered an opportunity that can make money because there is demand which exceeds supply for the service. As an additional benefit, such strategies are unlikely to run afoul of regulatory oversight or be eliminated through future rule changes.
> I think the markets are way too complex to rationalize "improving a market".
This is not rationalizing, it is about how to effectively identify profitable opportunities. Let's turn the argument around. Do you expect a trading strategy that harms a market to be reliably profitable without risking fines, banning, or imprisonment? If you don't, then it probably makes sense to exclude such approaches from your strategy search space. Additionally, I would argue that strategies which are of neutral benefit to the markets are likely to generate small returns relative to their risk because entities on the other side of your trades are not receiving value and thus the market is more likely to turn against you. If we eliminate "harmful" and "neutral", we're left with "beneficial".
I completely agree with everything else you say.
Non-trader here, what do you mean by a particular trading strategy "harm[ing] a market," how would you actually measure harm to a market by a given trading strategy, and would whatever metric you decide on for that not just be a dressed-up subjective argument?
What percentage of traders do you think will approach the market with such altruism?
I think the markets are way too complex to rationalize "improving a market". Markets are by definition good markets when you have long term and short term traders mixed in with technical and fundamental traders all with different alpha time horizons. This is a healthy market.
If you're a speculator, so be it. As you point out, the market may teach you a lesson at some point. Those guys go away but new ones will join.
It's a beautiful virtuous cycle.
Not to say there aren't bad actors. Most speculators are not IMHO. But they cross the line when they undertake certain market activities, like spoofing for example. This is why good markets also have good regulatory oversight (finra, sec... )