I am not an expert on this, but I have read that the problem with that sort of rocket is you have to go horizontally through the atmosphere for a long ways to g

I am not an expert on this, but I have read that the problem with that sort of rocket is you have to go horizontally through the atmosphere for a long ways to get up to speed. That produces a tremendous amount of drag that requires a corresponding amount of fuel to overcome. With a regular rocket you go vertical from the start and get out of the atmosphere in a minute or two, and then turn horizontal to get into orbit, and that takes a whole lot less fuel.