Ask HN: let's build a list of reasons why startups fail

I am writing a business plan for a new idea of mine. After all the reasons why this is the best idea ever and countless industries are going to be disrupted I am now writing "what could go wrong". This is the sad part but it has to be done. I have already several reasons in my list and I'd like to ask you here for some more. In the process let's build a list useful for all of us in the future. For this reason I won't even bother you with my "great idea" so we avoid "idea specific" failure reasons. I'll start with some obvious ones in my list:

* Nobody (or too few) need it

* Somebody needs it but won't pay/pay enough for it

* Budget underestimated (you needed more than that and you did not know it)

* Unproved assumptions ("we were sure it would go viral" / "critical mass is at X")

* Critical mass was higher than expected

* Somebody else is doing that already, better than you

* The big players see what you do, like it, and replicate it very fast. You're out

...and I am sure there's many more.

If we build this list properly it may be quite useful!