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.
You thought about this wrongly. Being successful doesn't translate to the same field of success, so the chain can't be how you viewed it. Everyone can be successful and still be in all fields. More so, if the economy permits it, you can be a teacher and be successful, but that doesn't stop you from teaching. Don't also forget about new graduates and foreigners who are ever ready to fill the space, if at all, there's a shortage.
Secondly if everyone own assets , the returns on those assets will drop. For example a house that give 8% rental yield would give 5 or 4 percent. So passive income will get harder.
That is true, due to supply. Is that not good? Housing inflation is a problem on its own.
Thirdly if too many people sit out and let money work for them productivity will drop. The highlighted point could be if everyone is trying to collect rent then who will pay the rent. You can't eat just the ice cream someone has to make it first.
This is not the reality of what can happen. Take a look at those people who even got good houses for rent at their young age, do they stop there? No, they continue working until they get old. This is the only life that could afford them more of those properties for their resting age.