Probably a typical takeoff stall. Too much climb without enough speed.
Also possible overloaded.
Article says it was 15 min. into the flight, not at take-off.
Weight and Balance perhaps. Also the PA-24 has had many different engines on the airframe ranging from 180 horse power up to 400 HP with 260 HP being very common. The 260 HP would have got even six passengers in the air even though probably over gross. The 180 HP would not if the aircraft also had a full fuel load. He probably got into the air due to ground effect and then crashed on the golf course at the end of the runway or engine failure.
This crash will wind up being either engine failure or gross pilot error. Very sad either way is this.
The PA-24 is really a very lovely aircraft with amazing performance considering when it was designed and built.