You can scoff but ISIS-K absolutely operates in line and accordance with US interests.

As a splinter group of Al-Qaeda connected groups they went into Syria, where there were plenty of reports of them operating in and moving through US-controlled areas and even operating in what appeared to be pincer movements with US forces. They came back from Syria with more money, weapons, and intelligence and started attacking a laundry list of US enemies:

• Non-US-friendly pre-coup elements in Pakistan
• The Taliban goverment and Chinese business and diplomatic delegations to try and disrupt trade deals, including a hotel bombing
• Iran, including the bombings of the Soleimani rememberance events as the US targeted Iran for support of Palestine and the Houthi blockade
• And now Russia, just as the US grapples with Ukraine being a lost war and their previous attempts at destablising Russia (economic warfare, sanctions, Nordstream, possibly Prigozhin etc) have failed.

Then you add in the fact that there's the overlap and collaborations between ISIS-K and TIP/ETIM trying to destablise China with terror and radicalisation, in the name of China's supposed Uyghur 'genocide'. With ETIM being removed from the terror list by the US supposedly because it 'no longer exists', which has been said to either be because those members have been absorbed by TIP/ISIS-K or because ETIM isn't conducting operations but now acts a convienient way for the US to more easily funnel money to TIP/ISIS-K.

It's also notable that in all of ISIS-K's operations, including in and around US-Israeli controlled Syria, it's never attacked Israel.

So you have an Al-Qaeda splinter group that served US interests Syria and got hands-off treatment by the US, that suddenly massively grew in scale, money, and ability, that only attacks US enemies and acts almost exclusively in line with American interests. Combined with the US's long, long, long history of funding extremist groups to carry out terror campaigns and proxy wars on their behalf.

So what's more likely? That this group might serve US interests and that America is doing the exact thing it's done consistantly since at least the 1950s? Or that your incredulous assertion that America could and would not ever do such a thing?