It wasn't the socons who became the biggest porkers. I think you are misled because W sounds like a socon and turned out to be a big-govt. guy. But the Congressional leadership who wallowed in the trough weren't the hard-core socons. They were careerist Party hacks like Hastert & Frist. They exercised no discipline and had no vision, as did Gingrich.
Well, I suppose that's fair. But, given that the social conservative has gotten a lot of their agenda accomplished, and given the at least perception that the GOP was a socially conservative party, one shouldn't be surprised if a lot of people think "we let them have their way, and look what they did".