There are also risks in financial markets that cannot be calculated, and in fact there are quite a lot of them. Just think about the impact of the coronavirus outbreak on the logistics of the world, and the impact of wars and various conflicts between countries. All of this hits the economic situation very hard, which in turn can affect the financial markets.
That’s a completely different thing, and I wouldn’t compare it to gambling. Sure, anything is possible, but we don’t live expecting things like wars to happen, especially something as catastrophic as one that could end lives, particularly if we’re in a country directly involved. That’s way beyond the scope of gambling risks. Gambling is about calculated risks and choices, while something like war is unpredictable and out of our control. They’re just not comparable.
And do not forget that gambling was invented to have fun and not for every gambler can increase their bankroll in 10 times a year.
I'm sure it is, but it's not impossible for a gambler to multiply their bankroll by 10 in a year, even though the chance is quite slim.