Well, actually you were right to recommend that he invest while he still has a job. In fact, I also thought like that, and at that time I was forced to invest. However, when I lost my job, I really felt the benefits of the investment. However, this could be a lesson for him that while he still has income, he needs to think about what things are good to invest in and not be quickly satisfied with his income at that time. Investments will help us when we have no source of income. Currently he has no source of income, and wants to invest in bitcoin which has quite a high risk of investing if you don't have a source of income. I suggest looking for income first, because I still adhere to the principle that don't invest using money you don't want to lose.
That will be a lesson for OP's cousin and he should change his life plans if he doesn't want to be in this situation again. But I don't think investment will help us in case we are unemployed because there is no guarantee that investment will always bring profit. Investment needs to have a long-term vision and must be completely separate from daily needs, only taking profits when the set goals are achieved. I think saving will be more effective in case we are unemployed than investing.
By the way, I also agree with you that the idea of investing while we are unemployed is a bad idea, and OP was clearly right in giving advice to his cousin.
It is to be noted that not all investments are good and suitable for everyone, some of them are not meant to be especially if we have a lack of interest and knowledge. We just imagine that not all investors are successful in this kind of investment but fortunately, they become successful in others. It has been the reality that investing depends on our risk appetite and we better not going to push through if we can handle the risk.
We have to remind ourselves that there is no quick returns investment (other than scams) and if we rely solely on our Bitcoin investment for our expenses, that is a big NO. It is a big mistake and a wrong investment plan as it has never been seen like that.