Why is Russell island waterfront cheaper than Sunshine Coast or Gold Coast?

Sunshine coast waterfront is usually surf, river or man made canals and marinas. Lots of people live there or want to live there, because of good infrastructure, jobs, education facilities/schools, uni's, hospitals etc. SMBI's are 4 x smallish islands with NO surf. There are some homes with deep water moorings on Russell, there may be other areas around the islands but I am not the person to ask I am not a fisherperson. Some boats have moorings between the islands, of Macleay, Lamb & Karragarra.There is still, for some, a bit of a stigma about the islands, mostly from people who have never been here or lived here! Some well off people live or have holiday homes on the islands. To be honest, I am not sure, why prices here are so cheap. The islands are like country towns surrounded by water, a boat ride away from the Gold Coast, access to Moreton Bay and great fishing. Crazy prices, high and dry land for $20k!!!