To be honest, no matter how good Bitcoin and other cryptocurrencies are, I wouldn't consider them sources that can be used to earn passive income because a passive income should be stable and you should keep getting money as long as your source is live, but when it comes to Bitcoin and other cryptocurrency investments, you don't earn when the market is going in negative but you start losing what you have already earned.
Passive income should be planned and it should not only depend on investment because fluctuating conditions sometimes force us not to be able to make a profit. Why do some people have good financial abilities because they have several sources of income and do not only depend on investment. That's why it is important to have a side job to make money so that we don't depend on all of it for investment needs.
For example, if you have $1,000 worth of Bitcoin when you are going to bed and Bitcoin is worth $30,000. When you wake up, the price of Bitcoin has reached $15,000 and you have $500 left, you have lost value when you were sleeping and a passive income doesn't work that way.
I agree that Bitcoin can be a great investment in the long run, but in the short run, you can't depend on it to earn you money constantly.
Bitcoin is indeed more reliable to invest in the long term because its value can increase at the time of the ATH moment. But in the short term people can also make a profit as long as they understand the market movement. Expecting to get passive income in one place is impossible, especially if it is related to crypto or bitcoin because we cannot predict the price with certainty. The short term is only used to make a profit and not think passively in making money.
There are many people who may understand how to trade but they spread several assets. So when one coin goes down they still have a chance in another coin. But this also does not necessarily give us passive income because the market talks about coins that are always fluctuating.