On David’s defense, he never said he did a new season because of greed. The exact quote from the interview is “
Apart from what he cheerfully describes as “pure greed,” this was part of why Duchovny thinks it’s worth another shot. “It was a great strength of the show,” he says. “The flexible frame. It could be comedy, it could be drama, it could be a thriller, it could be a horror movie, it could be a conspiracy movie, it could be a love story.” (x) And I think the “greed” part was actually referring to the original series.
They both clearly made a nice amount of money with the revival. I don’t think it was their only motivation to do it, and I don’t think it’s their only motivation to do a season 11, but if it allows them to keep working on low-budget projects that they enjoy and care about, it’s a win-win situation for them and us as fans. They’re happy and rich, and we have more episodes. Let Fox give them all their money!