Leopards are built for climbing with a carcass: a heavy forequarter, a broad scapula anchoring powerful shoulder musculature, and a jaw grip that can hold a load clear of the ground while the hind legs drive upward. Individuals have been recorded caching prey substantially heavier than themselves, including subadult ungulates, in tree forks several metres up.
The function is competitive. Lions and spotted hyenas take leopard kills readily when they can reach them, and hyenas in particular cannot follow a carcass into a tree. Where those competitors are absent or scarce, leopards cache less, and in some populations the behaviour is rare.
The common framing that leopards "always" store food in trees overstates a facultative habit. Caching depends on the local competitor community, prey size, tree availability and how quickly the leopard can consume the kill. The frequently repeated figures for the maximum weight hoisted come from single observations rather than systematic measurement, and should be treated as anecdotes.