They should have found the body if he hadn’t. He wouldn’t have been that far from where they found the money if he hadn’t survived.
I think he survived and abandoned the money that he dropped.
In the mid eighties, I wrote on the restroom stalls at trucks stops in Texas, LA, AR, OK & MS…”I am alive, DB Cooper”.
From the TV comedy "Newsradio":

On February 10, 1980, 8-year-old Brian Ingram discovered approximately $5,800 (about $6,000) in deteriorating $20 bills—three bundled packets with rubber bands still intact—while digging a fire pit in the sand at Tena Bar (also spelled Tina Bar), a beach along the Columbia River in Washington state.
The bills were confirmed by the FBI as part of the $200,000 ransom paid to hijacker D.B. Cooper during the November 24, 1971, Northwest Orient Airlines Flight 305 hijacking, based on recorded serial numbers.
The discovery occurred roughly 9 years after the hijacking. Many initially interpreted it as evidence that Cooper died, possibly by landing in or near the Columbia River without surviving the jump or parachute descent.
The text argues against this interpretation, asserting it supports Cooper's survival instead. It states the aircraft's flight path after takeoff from Seattle followed Victor 23 airway southward, tracked precisely by U.S. Air Force SAGE radar (accurate to within about a quarter mile) with no uncertainty in the plane's location.
Cockpit transcripts recorded a "pressure bump" at approximately 8:11 p.m. (widened here to 8:10–8:13 p.m.), attributed to the rear airstairs slamming up after Cooper's exit, causing a sudden pressure change.
With northeast winds around 10 mph, if Cooper opened his parachute promptly, he would have drifted 2–3 miles northeast from the exit point. The FBI's estimated drop zone placed his landing near Highland, east of Le Center, roughly 15–20 miles north of where Flight 305 crossed the Columbia River that night, and significantly farther from Tena Bar.
The text contends that for the money to reach Tena Bar if Cooper died in the drop zone would require improbable scenarios, such as someone discovering his body, removing the money bag, burying the remains and gear thoroughly (with nothing found in decades), then transporting and burying or discarding the cash 15+ miles away on the sandbar.
It dismisses alternatives like money detaching from the stairs and falling precisely over the river during a brief crossing window.
Thus, the text concludes the money's presence at Tena Bar—far from the calculated drop zone—is stronger evidence that Cooper survived the jump and moved the cash himself, rather than any death-related dispersal. The mechanism by which the money arrived at Tena Bar remains unexplained.
Who do you think kidnapped Nancy Guthrie?
Who knows?
Good question.
Cooper tossed some of the money as a ruse to lead people to believe he died in the jump. Rivers are notorious for migrating their channel, maybe that sort of thing complicated the eventual location of the money

I’m thinking he made it, and he had help waiting on the ground. Possibly on a dirt motor cycle to manage the terrain and get out of dodge quick. If he didn’t survive his ground help took care of the evidence. Maybe the cash was laundered out of the country?