• Can gambling or crypto trading/crypto investment be considered as a skill?
Of course. A lot of traders/investors(the successful ones) do a lot of research.
How is trading or investing a skill? Skill is something, that you do frequently and master it in a level that you do that particular job in a professional manner, quickly and efficiently. Let's take a carpenter as an example. One can't be a good carpenter without regularly doing this job and without involving in a lot of different and difficult cases, you can't repair wooden objects with any luck, you need skills, a good mind-muscle connection too while trader most likely depends on luck.
You are getting something wrong here, don't let the artisanship mindset mislead you, what you can use your brain to cleverly achieve is a skill, it doesn't have to be physical things like carpentry. And yes, people can apply their skills to trading and investment, learn the skills of trading and also use it to make money if works for them.
The only difference is that you might be needing luck directly in trading to profit despite showing your skills in it. But that doesn't mean you will not be needing luck in artisanship as well since you might be so skilled in it, yet you will need luck to still sell your products and services.
In other words and in plain terms, skills don't have to be physical as you misconstrued it.