I would tell these people to move out to a different city that has lower rent but I know people flock to major cities for jobs in the first place. I suppose having homeless people, of some certain non zero amount, is the reserve army of labour in marx theory, the elites want these people around to keep wages down. I know why you think rent controls dicentive further development but I don't really care about further development. I would want first everyone have enough to make ends meet and then we can worry about development. Rent controls could be removed once real wages are high enough to make sense to raise them.