It's like design or photography or consulting, entrepreneurship is something that is hard to put a price on. Entrepreneurship is a process not necessarily a product so it is tough saying, for your work, it will cost this much. People don't know how to value it but it is one of the most important pieces in company sustainability.
Often the founder's bills are the expense that no one pays. Most entrepreneurs push it off as, "it's my passion" or "I don't need pay, I just love to do it" but that's unsustainable. If you are working a day job so you can afford to work on your passion, you are working on your passion with an arm behind your back. VCs and angel investors know this and they'll tell you it's not a sustainable way to run a company. You have to put a price on your time (a sustainable price) and factor it into the cost of your company.
Sure there are thousands of entrepreneurs but few great ones, and the great ones get paid for their time. It's like the old adage, "dress like the job you want not the job you have" - if you want to be a great entrepreneur get paid or at least show a VC you know your work has a value to it - or else they won't value your work.
Have you valued yourself and if so, have you been sticking to it?