Homeless people may gamble with the money they're given.

Gambling addiction is 10 times more common in the homeless population than in the general population^[1]. Surveys in several different cities have indicated that up to 22% of homeless people were either currently gamblers, or had lost their homes due to a gambling addiction^[2]. This particular type of addiction does not have any physical markers, so it is next to impossible to tell if the money that you are giving will be used for necessities or at lotteries and casinos. A homeless person has more reason than the average individual to find appeal in gambling; not only is there the prospect of wealth, but gambling venues may also provide temporary shelter, a bathroom, and a social setting^[1]. Gambling is also a form of entertainment that incurs feelings of excitement and happiness - considering the fact that depression is extremely prevalent in the homeless population^[3], this could be a way for a homeless individual to escape the stresses of everyday life^[1]. There is no way to know whether a beggar has or doesn't have a gambling problem unless they choose to disclose that information to you; thus, giving money to them directly is a bit of a gamble in and of itself. By donating money directly to a homeless person, you may be harming them more than helping them by fueling their addiction, making it much harder for them to improve their living situation. This is why charities warn against giving money directly to beggars^[4]; you should instead give to organizations that have the expertise and resources to provide the homeless population with what they really need.