If you are specifically referencing U.S. Marine Corps paratroopers, they were not used in Europe. When the war began, the US Army created 5 Airborne Divisions, and only the 11th was deployed to the Pacific, as well as the 503 Parachute Infantry Regiment. The Marines did create 4 battalions of Marine paratroopers, but they did not see actual parachute insertions (although a few were planned).

There are two key reasons actual jumps weren't used as much in the Pacific. One is the terrain. For much of the operations in the Pacific theater, the terrain favored only a very few areas of approach. You couldn't just pick any side of an island and go in there. You needed a proper landing beach, and just as well, to land airborne or glider troops, you need VERY favorable terrain, which was not often available. Besides that, airborne ops are very tricky, and nearly every one undertaken in WWII was rife with problems. Even when everything is planned right, things will go wrong. When the 503 PIR jumped onto Noemfoor Island in 1944, the jump was too low, causing over 100 injuries from hitting too hard.

The second issue is that for the Marines, their Raider and Paramarine units were used to (moderate) success as assault forces into 1943 in the Solomons and the ill-fated Makin Raid. Although they were well-trained and fought well, they had to always contend with being an "elite within the elite," which never sat too well with higher ups in the Marine Corps, and they also had to face the growth of the Corps. With the need to to build two new Divisions, the Marines needed personnel to fill them, particularly with combat-experienced men. Most of the paramarines were moved into the 5th MarDiv, many of them serving on Iwo Jima as regular infantry, although they were still jump qualified. Harlon Block and Ira Hayes, two men who were part of the second (and more recognized) flag raising at Iwo Jima were paramarines, as well as Hank Hansen, who participated in the first flag raising.