Yes, travel insurance is worth carrying for a trip to Sao Paulo, though the honest case here leans more toward cost and everyday urban risk than any dramatic medical danger. Brazil's largest city has a genuinely strong private hospital sector, so the real reasons to insure are the cost of that private care for a foreign visitor, ordinary city-crime exposure, and seasonal flooding rather than a lack of quality care. Business travelers passing through for meetings around the city's commercial districts face the same practical exposure as anyone visiting for leisure.
Sao Paulo's private hospitals are considered among the best in Latin America, well ahead of what many nearby destinations offer, but that quality comes at a real price for anyone without local coverage. Check whether your existing health cover extends abroad and specifically to Brazil before you travel, and look for a policy that settles directly with a hospital rather than one that only reimburses you afterward, since upfront private-care costs here can be substantial, and check whether the policy settles directly with a hospital rather than requiring you to pay first.
Petty theft and opportunistic robbery are a genuine, well-documented feature of daily life in a megacity this size, particularly around crowded transit hubs and busy streets like Avenida Paulista, and it is worth insuring belongings accordingly rather than treating the risk as exaggerated or ignoring it. A policy with solid baggage and valuables cover, plus assistance you can actually call, matters more here than in a smaller or lower-density destination.
Sao Paulo's summer rainy season, roughly December through March, regularly brings flash flooding that snarls traffic across the city and around Guarulhos International Airport, disrupting transfers and connections with little warning. Keep any police report for theft, hospital invoices, and airline documentation for weather-related delay, and check your policy's claims process for both an urban-crime incident and a flooding-related disruption before you rely on memory later.