In fact, by renting out an apartment, the investment profit can be obtained within 1-4 years, where I once asked a rental owner who had 6 residential doors, in 3 years the construction funds had been returned and the rest he got profit
I think it is better to rent it out than to sell it
In the right area and with all construction done by the owners themselves I can believe its extremely profitable at times. Business should be more profitable then selling it as it involves greater risk. The court cases relating to tenancy contracts can drag on for years and still cost thousands in both damage and lost rent even if found in your favor.
Under 10 years for a return is quite common even in a normal 'quiet' area presuming no surprises occur. I know of a landlord who ran multiple occupancy short term letting and got back the entire house cost even though they had no money and loaned everything from a bank. It was still a job to let out and manage the property and made money, not an easy job always.