They might have taken whatever they could from Ghaddafi; regardless, the House of Saud is quite wealthy and has been for many decades. The US is and obviously has been an ally of the House of Saud. Oil, clout and geopolitics.
The Kaaba or generally speaking Mecca was not under the control of the House of Saud (Saudi) Arabia, as you know. It was under the control of the (Turkish) Ottoman Empire right up to WW1. (Kingdom of Saudi) Arabia was established thereafter, by the British?
Such prestige to have a piece of land, sacred to Muslims of all sects, controlled by a (Saudi) Arabia - becoming the Custodians. More so, in recent decades bringing the dollars from socalled 'tourism' ie pilgrims from all around the world. Whether they follow 'purist Islam' or not vis a vis $$$ was a secondary consideration, I would presume. So long as (Saudi) Arabia tried to appease & protect the pilgrims and the rest of the Muslim world.
Why does the House of Saud fund ISIS, AQ, etc..?
Because they can for now, as ridiculous as it might sound.
As I said in earlier post, ultimately for them, they are playing with a double-edged sword. So long as the prestige and being the Custodians of the holiest land of the prophet is under their control & was accepted to be so by majority of ALL other muslims, they think they can control within their own land whatever horrors they unleash elsewhere.
In regards to the picture you posted, one of the wives wearing western outfit with hat and all, has more to do with adjusting their 'politics' for their western allies - call it a tribute, their antics. Burning candles at both ends, whilst also funding (much less than secular) Islamic educational materials in primary schools in western countries, especially in the UK.
Sad thing for the House of Saud, and incidentally for most other "Kingdoms" in the Persian Gulf, for example Qatar comes to mind too, they can't continue to successfully strike a balance between appeasing the west, and many of their Muslim counterparts. Sooner or later, they'll either have to make a clear choice or be put out of business - that's my guess.
The Islamic caliphate in the levant plan to give everyone that choice.