Put a cap on profits made by private landlords

I want the Government to put a cap on how much profit private landlords can make on renting out properties. This will hopefully reduce the amount of landlords buying properties to rent in the first place and will make renting cheaper, giving people who are still struggling to get on the property ladder themselves a better chance to save for deposits. Many people pay nearly all their wage on rent alone, and many can't afford to rent at all, leading to homelessness.