Even crypto trading is can gain so much money in some quick time, don't forget that crypto can also lose so much money. And note that not all people can trading.
And I don't think trading can be main job (maybe there is anyone do that but still, they need a job to make money to be traded) And if a country only depends on trading, I can say that the economic would be destroyed and maybe the country would be bankrupt if crypto price down to the floor