Probably a lethal case of weekend pilot syndrome, perhaps with a touch of gonna-fly-today-itis as well. Especially among older pilots, essential skills tend to decay unless they are exercised frequently enough to remain fresh. Since the sky and airplanes want to kill pilots, all it takes is a small mistake to end up dead.
We had a saying in the Air Force:
There are old pilots,
There are bold pilots,
But there are no old, bold pilots.
It’s adding that Z coordinate to the X & Y that causes the issues.
You’re killing me, Smalls!
The two primary causes of civil aviation crashes; fuel mismanagement (running out of gas) and flying into conditions you are not prepared for e.g. weather. Saturday’s weather in that area was iffy and deteriorated badly in the late afternoon. The Cherokee is a nice little plane but not for adverse conditions.