In Why Smart People Have Bad Ideas, Paul Graham writes about some of the mistakes he and Robert Morris made in their first venture:
Viaweb wasn’t the first startup Robert Morris and I started. In January 1995, we and a couple friends started a company called Artix. The plan was to put art galleries on the Web. In retrospect, I wonder how we could have wasted our time on anything so stupid.
He goes on to identify three main reasons Artix was a bad idea:
We did the first thing we thought of; we were ambivalent about being in business at all; and we deliberately chose an impoverished market to avoid competition.
It’s worth a read.