I don’t get the economics here. It doesn’t matter who manages the money (apart from the fact that your savings go to someone who is barely able to assess risks), the landlord only keeps the average interest. Why can’t a tenant invest the money themselves and pay the interest to the landlord as usual? Why transfer a principal part as a loan? It doesn’t make a better interest rate.
Jeonse scheme sounds crazy to me: you basically provide a loan to an individual - one of the worst risks in my book, which has indeed bitten hundreds of asses according to $title. Individuals die, disappear, go bankrupt, go to jail, become motivated to screw you. Personally I wouldn’t give more than $1k to a random individual without a proper collateral, no matter how good the legal system works. Trusting them all your savings? That’s insane.