Important and beautiful things in life must be felt and experienced – they cannot be explained. This same happens with aficion, literally meaning affection: an interest, an affinity, a devotion, some deep fondness, which can be used in many different contexts (sports, music, food), but acquires a deeper meaning when related to wild bulls.
From the earliest years, some glare at the traje de luces (suit of light, literally, meaning the matador’s suit) and take the toreros as their idols and role models. Some just find it cruel and unnecessary.
On European latin countries (Portugal, Spain, France) and some Spanish ex-colonies, (Mexico, Peru, Equador, Costa Rica) society is polarised in this regard, with demonstrations laws, and many written pages on both sides. Unsurprisingly, politicians have used it to earn votes.
I was one of those, born with aficion. While my school friends memorised the names of soccer players, I knew all the major bull fighters by name, and could evaluate their performances.
The phenomenon goes far beyond the Bull rings. People want to be a bullfighter for some moments, either taking lessons on how to use the capote (originally a cape) and muleta (literally a crutch, meaning, a smaller version, with a wooden stick attached); or jumping into the arena, wether on a bull ring, a square or a street, closed for the effect. Some will just run away from the bull, some would jump over, defy it with capes, umbrellas, pieces of fabric or their bare hands.