I can't speak to YC specifically, but one normally would want to contact many investors in parallel. The chance of receiving funding from any one investor is i

I can't speak to YC specifically, but one normally would want to contact many investors in parallel. The chance of receiving funding from any one investor is incredibly low. If you contact them serially, you'll spend a hopelessly long amount of time raising money. Likewise, if multiple investors are interested in your company, they may jointly invest, which is somewhat common. Plus, you can use the competition to establish the fair market price of your stock.