Why isn't spicy actually a taste?
When chili burns your mouth, your tongue is not tasting anything - it is feeling pain.
Spicy is not one of the basic tastes. The heat comes from capsaicin, the compound in chili, which binds a nerve receptor called TRPV1 - the very same sensor that fires when something is burning hot. Your brain gets a heat-and-pain signal, not a flavor, which is why a chili can make you sweat and tear up like a real burn.
Bite into a bowl of bun bo Hue loaded with sa te and your mouth burns - but milk or rice calms it while water just spreads it, because you are soothing an irritated nerve, not rinsing away a taste.
Spicy is a pain and heat signal, so reach for milk, rice or yogurt to calm the nerve - water only spreads the capsaicin around.
Knowing spicy is pain explains why water fails and why chili tolerance is your nerves adapting, not your taste buds changing.
Spicy rings the fire alarm, not the flavor bell - same nerve that says the pan is too hot.
Learn the idea and practice English at the same time.