Just wondering -- I don't have kids yet, but I'd be worried that all that money/security may not be enjoyable if I hadn't built my relationships with my kids when they were young.
[edit: sorry for the offtopic, BTW.]
There are many others, the opportunity cost to your corporate career for example. The reduced bank account balance from where it could be if you sold your soul. And the list goes on.
As much as we like to romanticize the process, there are a lot of risks and pitfalls. Luckily for a lot of us, it is not a choice and we just aim to minimize these hurdles!
My kids are the most important thing to me and, in life, you make trade-offs: bigger house or nicer car? Get my teeth fixed or go to the Bahamas? Work 50 hours a week doing something in which I have little control for 50 years or work my ass off for 5-7 years so that I have control for the next 45 years? That's how I see it.
"Hard" - maybe that sounds silly in that context, and lazyness is my only problem, but I don't think so. Even while consulting I dream of working on my projects on the side. From experience I just wouldn't plan for it to succeed. Also, my health is very important to me, also in terms of longterm security for the (prospective) family.
No ####! Of course it's hard. Do you think I wanted to work 70-80 hour weeks or play with my 2 year old? I wanted to play of course but the long-term vision of creating lifetime security for my family over weighed the short-term work. Read PG's essay "Inequality and Risk" (http://www.paulgraham.com/inequality.html) for more.
I don't know YC's deal but can you tell me whether or not the term sheet they put in front of you is a good one? If you say, "I don't know" or "No" or if you haven't even thought that far, I'd say you are rushing into it. I would guess that, if you have the mindset of, "If I get funded I'll do it", it's gonna be hard to get funded.