90% of Yemen was liberated, all the areas with all the natural wealth (oil and gas), 90 of the coastline. Houthis were/are confined to the mountainous northwest. KSA was never interested in going after them as it would be a losing battle - similar to US/Pakistani attempts of removing the Taliban - never going to work in this terrain and with such a large population (North Yemen has 20-25 million people). More so when the Houthis are embedded within civilian areas. There is also the "problem" and "dilemma" of North Yemenis being fellow Muslims and Arabs that we are closely tied to. In particular people of Southern KSA - one of our most inhabited areas. There was always deep unpopularity with this war among many circles within the Saudi Arabian army. Hence KSA was mostly limited to a support role for the Yemeni army, engaging in key battles such as the battle of Aden and other such battles. Rest was sporadic special operations and air and naval warfare.
Maybe it is the Iranian regime that needs to learn with its neighborhood in peace? You are talking about a country that has attacked every neighbor from Turkiye to Azerbaijan to Iraq to Oman (you know those guys that they themselves handpicked before the war started as a place for negotiation - preferring them over Turks, Pakistanis and others), to Syria, to Pakistan to GCC. Not long ago they attacked you guys with ballistic missiles.
They are the only regional country that I know of who have actively used 1000's of Pakistani Shias as cannon fodder in Syria and elsewhere.
KSA did not allow offensive operations from its territory UNTIL Iran, in desperation and because they cannot hurt either the US mainland or Israel really, started to send drones and ballistic missiles at KSA. Not the other way around.
And no, there are no US bases in KSA. This is a Saudi Arabian sovereign military base (Prince Sultan Air Base) which has been allowed to be used by the government by the US as a logistics hub mainly. It only became relevant 10 + years ago when the whole Daesh menace emerged. Due to being centrally located between Syria and Iraq in the north it was the perfect staging (one of many in the region) to wage air raids and campaigns as well as being a logistics hub situation in the middle of the Arabian Peninsula bordering 2 of the world's most important trade routes and bordering Africa and Europe and Asia next door.
And the Iranian regime is not very clever. Do you really think that by attacking those small GCC states the regimes in power will somehow now reduce US presence? The opposite is already occurring. As if this was any surprise. The Iranian regime has given the perfect excuse for leaders in Qatar, UAE, Bahrain and Kuwait to say that we need US bases because otherwise the Iranian regime might even invade us (of course unrealistic) but you get the point.
But even if the GCC did nothing at all, Iran would also be attacking the GCC (desperate attempt mostly and with little to no harm) due to geographic proximity and the oil, gas, aviation and economic hubs that the GCC Is. The plan was always to make a regional war (Iran vs US or Israel) into a world/global war in order to use oil/gas/global economics/trade as a power play against rivals (US, Israel) that Israel otherwise stands no change to win against militarily. It is pretty simple.
Why was Oman attacked numerous times for instance? Nobody believes the Iranian nonsense about some imaginary US or Israeli attacks. It was confirmed that those were Iranian drones and missiles as well.