If everyone becomes landlord, investor and owner then who will become Doctor, engineer, teacher and farmer? There would be shortage of labor who give services and wages would spike for such jobs.
I don't like seeing such from the perspective of gloom. I like to see it from the possibility that it exposes us to more career choices. A lot of us here have more career choices and skills than one. Someone can be two or more of the above listed careers. Nothing says it's an aberration. In my country, there are lots of people like that. For instance, one of the top crypto influencers in Nigeria I know is a trained medical doctor. I don't see any shortage there.
On top of that, if you make X amount of money from being a landlord, then why not be a landlord AND a doctor that makes 3X? That's the main reason. Not that the whole world could have passive income, that's not how math works, so the question in itself is wrong, you can't have this. There isn't enough money in the world that would make it possible for the 8 or so billion people ALL to have capital to put into something where they all make passive income, it's impossible, there isn't enough money, math doesn't check out.
But even if we assumed that it's possible, and lets say not all make it based on homes, because if we all owned homes, then who would rent from us? Let's say it's stocks with dividends, or bank savings accounts etc etc. In the end, some of us would make X amount, and others would want to start a business or work to make more.