[refurb]

If you spent 30M and bought 30-40 houses to rent out, you would be contributing to society by risking your capital to provide housing for renters.

There is no certainty that you’d double your money in 10 years.

[asdff]

You aren't contributing to society if you charge more for rent than mortgage and maintenance, you are a parasite.

[refurb]

Why? If Apple charges more than the cost to manufacture a iPhone, are they a parasite?

If not, what’s the difference? The are both offering a good.