it is called speculation, not gambling. One of the big differences is that in gambling you do not have an advantage over the casino, they have the edge on you. In speculation you are taking an educated risk that something will happen based on study and investigation
That something is called luck in gambling, and you know the odds beforehand (unlike trading)
You should know difference between "Dumb money" and "smart money" . Smart money isn't looking for short-term profit, it needs edge over the long term. Big banks and hedge funds are looking for 10%(!) profit in one year. They dont put all eggs in one basket: Portfolio investing, future contracts It is all about risk management and skill. In gambling you need luck and little bit experience
That's bullshit, moreover, it is potentially fatal bullshit if you are really going to follow it in practice
Forget about Harry Markowitz and his ideas about portfolio management. They don't work in real life since his is a theory based on premises which never occur in real life (many people have burned their fingers following it). Big fish are earning by eating small fish, this is what all trading and investment theory can be reduced to. In other words, if you belong to the latter, you basically have just two options, i.e. either to end up eaten by the big fish at the end of the day or stay away from playing games against "smart money" since you will be playing by their rules, i.e. inevitably end up eaten by them sooner or later. If you can outwit and outsmart them somehow, then more power to you (the dudes in line after you will have harder times if you succeed). But that would have nothing to do with risk management and not putting all your eggs in one basket, anyway