I agree. In most cases, bitcoin is obtained as a small temporary part-time job which can only bring a big profit in a few years if it is saved and wait for the price to rise.
Are you sure a signature campaign does not have an employer? Then who is paying us of our job/task? Isn't it the owner of the campaign? Managed by the manager? Signature campaign does not fall under self-employed category because you are applying for the position or slot.
And they maybe a part time Job or sidejob as the other stated (see bolded word). We are not discussing here about the quality of job or the how the job is created or how long it will last. We are discussing employment and unemployment. If you applied for a campagin and got accepted won't you considered yourself employed? If not then what do you call it?