Why are there so few young organists?

Let's go with these reasons as a beginning:

1. Church and symphonic organs are large installations, they are not portable instruments.

2. The cost of an organ is well outside the reach of a normal person

3. Churches have moved away from quality music programs in lieu of drums and guitars in an effort to "get butts in the seats."

4. Churches that continue to use the organ are generally not open to having "students" come in to use the instruments, and their organists are either unqualified to teach or have no desire to teach. Many church organs have fallen into disrepair through neglect and no funding to maintain the instrument.

5. Very few organ manufacturers that build home organs exist. Nobody knows how Lowery continues to "thrive" considering their product line. They are sold almost exclusively to the retirement community.

6. Rodgers, Allen, Johannus, Ahlborn-Galanti, Viscount, Content, Phoenix and a few others continue producing the traditional organ console with digital "guts", but are still very expensive and are marketed toward Church installations.

7. There's very little interest in what is essentially a large solo instrument both from the player and the audience side.

... on the other hand Gert van Hoef is a serious up-and-coming organist. Felix Hell and Cameron Carpenter are well established young organists (perhaps the E. Power Biggs and Virgil Fox of the 21st century). Barbara Denerlein is always entertaining with her Jazz interpretations.

It's probably because not as many youngsters these days aren't being exposed to the organ. Even if they are exposed to the music of the organ, the organ is much less accessable than the piano. Most households would have a piano over an organ.

I have a friend who learnt the organ at a younger age but she is religious, went to church, and used their organ.

It is quite uncommon for someone to have access to an organ. Also the difficulty of playing with your feet and multiple keyboards could deter those that do have access to one.

Technology. Even grand church pipe organs can be retrofitted to be played by a computer. MIDI killed the organist.