Actually, it is possible to have a passive income stream based on crypto. Maybe by using some idle money, investing in mining, I think that is one way.
We cannot consider mining as trading, but mining is just an investment, where you put your money for buying the devices for mining. It is not trading, in trading we always do buying in low and then try to sell it in high price, but investment is something different where we invest our money for getting a regular profit from some source.