- I would like to hang out with like-minded, serious startup folk in San Francisco.
- I would like to meet a seasoned entrepreneur and have a chat about my plans.
- I would like an introduction to a few investors to bounce some ideas off of.
For those three things, I am not willing to give up 5-10% of my startup, which is profitable, and relatively mature compared to YC investees. Additionally, I am sure a full-fledged YC investment offers far more than those three points. ;)