Huh. Never knew this was uncommon… just never thought to ask anyone. I was born in the mid-70s to a mom from the late 40s, and we ate rice as a sweet cold cereal as I grew up. It wasn’t leftover rice, either, but rice fresh-cooked for breakfast. Sometimes with raisins added during the last few minutes of steaming to plump up, then dished out, sprinkled with sugar, and covered in cold milk. The combined sensation of warm rice and cold milk was great.
We also added milk to cooked oatmeal and cooked CoCo Wheats to make a thinned-out breakfast dish… just tastes better than the gelatinous puddles of goo they’d be otherwise.
My dad was also born in the 20’s. He would make it with milk, sugar and cinnamon. I remember it being served cold, but it may have been heated sometimes. I don’t recall him making this recently, though.
Dad was born in the 20s and often ate leftover rice with milk and sugar on it for breakfast the next day. It wasn’t anything like rice pudding. Rice pudding requires eggs and baking.
Caution: eating rice that has been left out at room temperature too long can give you food poisoning.