I know some Vietnamese that do similar. Friends of my wife have 2 houses in Regents Park with a Granny Flat out the back as well. Family live in 1 bedroom together and rent out the rest of the rooms individually to international students.
Personally not for me, I grew up as the youngest of 4 once I could afford my own place the last thing I wanted to do was to share it with anyone but my wife. Everyone values things differently but for me the extra money isn't worth the privacy you're sacrificing by sharing your home.
