My personal thoughts are that it should be possible to start a company overseas, get far enough along to secure $250k in VC funding. Also, I would be surprised to find a successful startup that can't get $1m in revenue within 2 years.
While a VC can control additional investments, they have less control over revenue than most founders. A successful start-up should not be dependent on VC funding after 2 years unless it grows exponentially and needs the funds for growth.
Also the terms after 2 years are less than for an existing EB-5 visa.