The IRS thing can be 100% planned for. There's no good reason for it to be "unexpected." Note that "Too lazy to draft a comprehensive business plan" does not count as a good reason. Unexpected demand in excess of one's ability to handle said demand is a legitimate issue. That said, Kickstarter already has a mechanism in place that allows project developers to limit the number of backers that they will accept, if they want to. (I guess I should clarify that technically, it's a means of limiting the number of rewards that you will give out, not the amount of backing that you will accept. But it amounts to the same thing).