To keep loneliness at bay, street children often band together in "families"or form close knit partnership:

What exactly is a street child?
Anyone who works with street children comes up sooner rather than later against the problem of definition. Broadly, street children are those for whom the street (in the widest sense of the word: unoccupied dwellings, wasteland, doorways, sewers…) more than their family, has become their real home, a situation in which there is no protection, supervision, or direction from responsible adults.
In the 1980s, UNICEF and other agencies suggested a distinction between children ON the streets and children OF the streets. “Children on the streets” or “working children” are those whose family support base has become increasingly weakened and who therefore must share in the responsibility for family survival by working on city streets. While these children may spend their days and evenings on the street, they usually return home at night. “Children of the streets” are those whose ties with family are completely broken and who are completely alone, without support (even the support of extended family, step-family, or god parents) and must struggle for daily survival.
Although the UNICEF definitions and categorization are helpful, they are not so easy to apply. [For example,] here in Cusco [ Peru], there are children who live in the streets on weekdays but go home on weekends. There are also those who would be considered “on the streets” but who stay away from their homes for extended periods of time. “Of the streets” kids might not be in the streets continuously; at times they are in jails or institutions or they are living with unrelated people rather than their families. Child prostitutes often do not fit cleanly into these categories either.
The UNICEF distinction assumes a more experience of family life where the family lives in a private dwelling where the front door is shut against an apparently hostile world. It denies the reality of slums and provinces where overcrowding forces play, culture, and family life onto the streets. So then, children on the streets within their own communities should not be considered “street children”. Thus, a street child is not just a child on any street but a “child out of place.”
Children often end up on the streets due to rural-urban migration, family unemployment, and poverty. Most people who work with street children will agree that few have been abandoned. Rather, street children tend to gradually abandon or break away from their families. Usually abuse or exploitation within the home is involved, often associated with parental alcoholism or drug use.
In recent years there has been an overconcentration on “children of the streets” which has hidden the problems of larger groups of working children who are not so visible, exciting, and glamorous, but whose problems are no less urgent. Generally working children tend to be lonelier and suffer from greater abuse. They have less freedom. The nutritional status of many working children has been shown to be worse than that of children of the streets likely because they must share their earnings with the whole family. Studies have shown that their physical, psychological, and intellectual development has also been more damaged. All children living even part time on the streets encounter violence on a daily basis, often at the hands of police who are after all paid by society to keep the streets clean and safe. In the street, the notion of children’s rights takes second place to the requirement of avoiding tourists being made uncomfortable by unsightly beggars. Many experience detention centers or even adult prisons which leave them physically and emotionally scarred.

The street children that I have talked with have told me that it is impossible to survive in the streets without using drugs such as terokal (a toxic glue used for shoes), crack, and cocaine. Membership in gangs and sexual relations (often spreading HIV and other diseases) are also common.