The man who produces while others dispose of his product, is a slave. Rent controls are perfectly legitimate because this is a democracy, and rent controls have been voted in. Just because the majority votes away your property, that doesn't give it a moral right to do so. If majority rule were the only basis for deciding what the government can do, then 51 percent of the people could legitimately vote to enslave or even kill the other 49 percent. Hitler was voted into office and had great popular support.
All tyrannies are wrong, including tyranny by the majority.
The voters don't own your life or your property. Landlords are just being selfish by wanting higher rents. In fact, there's nothing wrong with being selfish rationally selfish. Selfishness means that you live for your own happiness, not that of others. You want the highest rent you can get, and tenants want the best apartment for the least possible rent.