Give a man a fire and he’s warm for a day, but set fire to him and he’s warm the rest of his life.

Terry Pratchett (1948-2015) English author

Discworld No. 21, Jingo [Jackson] (1997)
    (Source)

Variant: "Build a man a fire, and he'll be warm for a day. Set a man on fire, and he'll be warm for the rest of his life."