Why is there a significant discrepancy between the estimated number of objects in the Oort Cloud and the observed number of long-period comets?

The Oort Cloud is thought to hold trillions of icy bodies, but only a tiny fraction ever get nudged toward the Sun by passing stars or the Milky Way’s gravity; most stay far out. When a comet is pulled inward, it must survive the Sun’s heat and tidal forces, so many are shredded or evaporated before they become visible. Even the ones that survive are very faint, and we can only detect the brightest ones with current telescopes, so the sample is heavily biased. Thus, the huge theoretical population contrasts with the handful of long‑period comets we actually observe. For example, a comet that starts 50,000 AU away may be pulled in, brighten, and be seen for a few weeks, while the rest of the Oort Cloud remains unseen.