With the need to sell off the government bonds, interest rates must be pushed up (very obvious first condition). After this, it makes the prices of bonds decrease (rates increase = price decrease), and thus increases the relative price of investing in the future for anybody. Instead of spending X amount building a new real estate development, the option of buying bonds (of any kind) is more enticing. Thus, many future investments could be discouraged. It is nearly impossible to directly point to a number that this negatively affects, but it is important to recognize that this crowdout effect can have a negative effect on the capital investment and future GDP growth rate of the U.S.