• Can gambling or crypto trading/crypto investment be considered as a skill?
Gambling in general no, sports betting or poker yes.
• Can a gambler or crypto trader/crypto investor earn as much as $10k in a month besides any of the aforementioned skills?
Regarding trading, I agree with the following:
Yes people can do $10k gain in a month with Crypto, but obviously the thing is the list doesn't contains that how much capital you need for it. A person having $100k in capital, for him this gain might just be one trade away. But for someone with $1k capital it might be impossible even if he has the skills, trading is very different than other vocations therefore. Capital is the very important basic requirement that you have in trading. Also even in the skills you listed I still don't think they can give a "Guaranteed" $10k a month.
In poker, and in sports betting I think too, what you can win depends on the bankroll you have, as long as you are playing within a beatable level. To win $10,000 a month you must be playing mid-stakes at least and depending on the hours you put in. In both poker and trading we should take into account the variance. In general you could make $10K a month assuming you have the necessary capital/bankroll and the right skill, but that would be an average of the annual results dividing the profit in 12 months, of which some will have had losses and even if the variance is extended it can last a year or more depending on the mode (with tournaments it would be worse).
So the "guaranteed" thing is a bit difficult, the best for that would be a signed work contract that pays you that much per month, the other ways involve variability.