That sort of money could tip a half-dozen (or maybe a few dozen, depending on how good you are at this) close elections toward the candidate who thinks most like you -- and in the new, post-Citizens United era, no one will know it was you spending it. That will make a much bigger difference than taking office yourself. And then, when one of your candidates eventually becomes president, you can just get them to appoint you to the Cabinet position of your choice. And you'll probably have enough money left over to start a think tank or endow a research center or enlarge an existing institution devoted to pushing the issues you consider important.
That's Meg's real failure. She could have bought several House races instead. Instead she blew $140 million on her own ego. Epic evil corporate overlord fail.