I am not totally sure about national currencies but threat in job is absolutely possible to happen. Actually it is happening right now in the current scenario. I've known a lot of people who left their regular job coz they are already earning so much money here compare to how much they earned on their job.
I don't think crypto will be a threat to jobs but rather it will those who have no jobs. Even though on what you have said that lot of people left their job because of crypto but there are more larger of unemployed that will fill in the jobs they have left.The number of Job hunter will never decrease.