Property doesn't produce anything. If I buy a house for $500K and sell it a year later for $600K, that extra $100K hasn't been added to the economy. Something else had to make that money. It's just speculation.

Whereas if I invested that $500K in a company, the company makes things or provides services that add value. If the company grows to make my investment worth $600K a year later, that has actually been added to the economy.

Note that I'm defining property to not include construction, which is a separate thing, that does add value.