Come to think of it you could almost do that these days quite easily with automation.

Auto generate about 15000 tipsters and sign them up to some sort of proofing website. Only tip in fields of 5 or 6 horses and you suddenly can do :

5 * 5 * 5 * 5 * 5 * 5. It wouldn't even need to be that many.

You could concentrate on top 3 horses only :

3 ** 9 would almost get you there. If people saw you tipping 9 tips straight you would get enough signups from those "believers".