It's literally the basis for Thomas Piketty's 'Capital in the Twenty-First Century'. It's a dense book, but widely acclaimed. It was also published 8 years ago and the claims aren't controversial.

Real estate (land to be specific) is a popular investment because it lets you extract economic rents.

You can build a dynasty around land because ownership is barely taxed. Land does not degrade by simply keeping it vacant. Meanwhile everyone around the land needs it to live on or to work or to extract resources. Inequality isn't driven by well deserved high returns, it is driven by monopolistic extortion where you cannot refuse even if you know you're getting ripped off.