over how many years? for a 2m property, a 70% mortgage over 20 or 25 years is perfectly manageable.
And as PDLM mentioned. rent is not the only profiteering part. remember, as they are paid rent, they still own the flat.
example.
landlord buys flat for $2m
10 years of rent at $8k per month = HK960k
Sell Flat for $2m
Profit = HK$960k - repairs, expenses, agent fees etc etc.
... and that is if the property does not appreciate in 10 yrs.
It seems for alot of landlords, they are the older members who have already paid for their flat, but want to move to somehere bigger, and have a job to pay the new mortgage so any rent from the old property is purely a bonus.