[jeffreygoesto]

From my own (admittedly limited) experience with riding a Segway and my own (day to day) experience with a child that can't sit, stand or walk, I would guess that it is a) difficult to get in and out and b) difficult to balance and steer.

Extra mechanical stabilizers are in the way when you finally are on/in and without the Segway was really stubborn and threw me and others off in the beginning. A person without proper sense and ability to balance, will have big problems getting onto it and off again with just the gyros running. Also balancing is a really difficult thing to do if you have the problems that forced you in a wheelchair in the first place.

For people who are ok with the upper part of the body, and can lift themselves onto the machine, you might be right though. Unfortunately there doesn't seem to be a "used Segway" market that is cheap enough to attract hackers trying out new things with them.