In addition to the supply of capital (which is quite significant!), tax rates also affect the likelihood that the startup is successful. The higher the tax rate, the higher the company's burn rate, and the less time the company has to gain traction / positive cashflow.
The idea that the economy can be saved by entrepreneurs that never need to raise money is sheer lunacy. I can believe that the funding climate might not be someone's primary consideration when deciding whether to start a company; I can also believe that it might not have much influence on the very early stage growth of the company. However, outside investment still plays a fundamental role in the growth and success of most companies of non-trivial size.
The point is that entrepreneurship (at any significant scale) is intimately related to the availability of capital. That applies to all sectors of business, but particularly to capital-intensive ones.
