I am Brazilian and I can say
Main causes: 1. Poverty due to Corruption. 2. Lack of policing and unpreparedness due to lack of funds (Corruption) 2. Soft Laws (Brazil employed with the human rights ideology for bandits) 3. Unarmed population (human rights ideology for bandits)
Root cause of the problem: Corruption
Many decades of a corrupt government that spent all of Pais's resources to perpetuate itself in power. The question is: why did the Brazilian people continue to vote for the same corrupt ones?
"Social" programs, the government bought the poorest population with a monthly fee of $ 10.00 "Bolsa Familia"
The left had no opposition and bought them with the money of the "mensalão" and "petrolão" (see operation wash jet).
Lots of public money in progagandas
Purchase of votes and distribution of government positions.
Attempt to implant the left in a socialist country (see PT alliances with vat)