Bush money is not the reason he can win nomination.
It is dividing conservative voters among several candidates is how he wins. Very similar to Newt, Santorum, Cain, dividing the votes to alear the path for the lone RINO Mitt.
That money makes the operation much easier. He can spend big bucks to trash the leading conservatives in each of the first primaries until they are exhausted and broke and still have sufficient for the later primaries when he is actually running. The donors have watched that process work several times and assume it will work like that again. Theheavy trash ads do have a deciding effect in that as each conservative fades the donors write more checks to Bush.