This is actually more like science than TLB says. If you've been working on something for a few months and you haven't published or at least given a talk about it somewhere, one of two things is probably true:
a) You're a reclusive genius dedicating your life to solving in secrecy a problem many hundreds of years old; or
b) You're afraid to find out that what you've been working on was stupid.
Are you talking about only the web-startup domain, or life in general? I think there exist domains where you can't get something worth talking about done in a few months.
a) You're a reclusive genius dedicating your life to solving in secrecy a problem many hundreds of years old; or
b) You're afraid to find out that what you've been working on was stupid.
Guess which one is more likely?