What leads someone to squatting?
According to Merriam Webster Dictionary the official definition of a squatter is "one that settles on property without right or title or payment of rent." Based on this definition, there can be many reasons for one squatting.
Source 1
The most common squatters in America and the United Kingdom aren't people who are particularly impoverished but rather people who simply will not pay the competitive rates of rent in a particular area. The Melbourne Times tell a story of a 29 year old Ph. D students who turned to squatting because of high housing prices. “I just kept hitting brick walls when trying to find new rental properties or trying to find share houses,” [the student] said. “It was totally insane. I went to rental property inspections and witnessed the rent auctions that are so infamous now and just decided that I would start squatting.”
Source 2
In Europe squatting is often used as means to avoid rent. Most European nations have laws protecting squatters. This leads to a more important question: Why are so many governments quick to protect squatters?
What cities have the most squatters?
It is difficult to count the immense amounts of people squatting in the world, thus, there is no official stratified list of cities that have the most. It is known that there around 1 billion squatters across the world (1 in 6 living humans). Rio, Istanbul and Mumbai are know to be some of the worst. ~ ted.com
Are there gangs or packs of squatters?
Yes! In some cities there are actually squatter "villages". However, these are most prevalent in countries we consider third world, such as Brazil, or countries which poverty is a serious problem, like India or Turkey. Yet, it is important to realize that these villages are much less like the empty apartment villages most European squatters take over. They are literal shanty towns only the poorest people live at. ~ ted.com
