If you take money at a high valuation, the VC will only be happy if you try to grow the company significantly and exit at some multiple of that valuation. If the founder decides not to do that, then one of the largest shareholders in the company (the VC) will be angry. At a minimum I imagine the founder would be negatively impacted by losing some of his/her reputation in the investing space and having angst knowing that he/she took a VCs money and then ignored the VCs interests. At worst, there could be issues at the board level and loss of control of the company.