Money can buy a lot, but it doesn’t necessarily buy victory. Just look at Meg Whitman’s 2010 campaign, in which she spent $140 million of her money, yet failed to win the California governorship. Similarly, Linda McMahon spent nearly $100/voter in Connecticut, but lost the Senate seat.
Adelson’s money is likely to help Romney more than it did Gingrich, because Romney is the presumptive nominee and public support is behind him now.
The bigger issue is that the question assumes that the practice of giving money – especially a lot of money – to political campaigns is somehow “corrupt.” Contributing money to candidates, parties, activist groups, PACs – or, super PACs – is a good thing. It’s an opportunity for Americans to be directly involved in the political process, and it’s the basis for free political speech.
The fact is we wouldn’t be having this conversation had McCain-Feingold not imposed such strident limits on political giving. The 2002 law didn’t eliminate the desire to influence politics through money; it simply made it less transparent. Now wealthy donors like Adelson have to find “back-door” ways to contribute, and super PACs are just the newest fad in an effort to get around restrictive campaign finance reforms.