THE ON-DEMAND AIR TAXI FLIGHT WAS DEPARTING FOR UTICA AND WATERTOWN, NEW YORK. DURING TAKEOFF, THE PILOT STATED THAT HE FELT THAT HE DID NOT HAVE ENOUGH AIRSPEED FOR FLIGHT AND DID NOT THINK THE AIRCRAFT WAS GOING TO BECOME AIRBORNE. THE TAKEOFF WAS ABORTED AND DURING THIS PROCEDURE THE LANDING GEAR WAS RETRACTED. THE AIRCRAFT SLID ABOUT 300 FEET OFF THE END OF THE RUNWAY AND CAME TO A STOP.