That is the weak point of passive income generation. You must need diversification still you must need to do in massive volume yet that will lead to poor managing due to time constraint and lack of manpower availability. In my experience, instead of risking with third party things and altcoin related stuff, it would be highly secured and profitable if you try to make use of bitcoin with long term holding which might be definitely having good interest rate than 8% of your most of the things.

Yeah, bitcoin itself a very good opportunity to gain good value over the time passively. I bought bitcoin when it was trading below $1000 and I am still holding it and I spend zero efforts after buying and keeping in cold storage. That cannot be called as passive income generation?