Why do people bid on equipment and don't come

1) Change of mind
2) Testing the market
3) Sobered up and realize they made some drunk dialing mistake.
4) Spouse or SO found out about the purchase and nixed it.
5) Another better deal came up.

As to why they bother bidding in the first place:

1) Boredom
2) Loneliness
3) Obsessive/Compulsive behavior
4) Depression
5) Excitement (a la gambling)
6) Mind altering drugs (including alcohol)

Now that they have your PP address pay close attention to your account for any abnormal behavior. This time of year more than others is ripe for naughty behavior and people need mo money!

Be sure to report these people to Audiogon so they can be put on the 'black list' and not waste the time of others.