No aid is truly given for free. If a loan is provided, it's expected to be repaid with interest. If aid is given, it's often in exchange for certain privileges. Natural resources are exploited, sovereign rights are interfered with and the internal affairs of that country are meddled in.
Even when aid does arrive, there's no guarantee it reaches the people. Corrupt politicians often pocket the money and only a small portion of the aid benefits the public.
For poor countries to truly improve, they need to stand on their own feet, build a strong education system, have a fair legal system and get rid of corrupt politicians. Without doing these, they'll stay poor.