Because he was feeling crumby.
or
Because it would fall over if it lifted the other one.
or
I was amazed, I never knew they worked.
or
Four. One to change the bulb and three to whine "It's too high"
or
It's not a shrub, it's a lemon tree my dear Watson.
or
Seven. One to change it and the other six to sing about how good the old one was.
or
His breath.
or
Nearly unanswerable, since the one who tries to change it usually drops it, and the others call for a planning session.
or