I must wholeheartedly disagree with you on several points. My background: I was in Afghanistan in 2020 when the drawdown was actually happening up until the very end of the year, also working in a strategic level position.
1. The political spin. Look, I'm more inclined to support Trump than Biden in general, but trying to imply that things would have been different if Trump had been re-elected is demonstrating selective memory at best. The Taliban never met any of the conditions of the peace deal outside of a general reduction in violence against NATO forces, and even then, we still had about a dozen NATO soldiers wounded by Taliban attacks. We were still going to leave according to the timeline regardless. Furthermore, everyone on the right is conveniently forgetting the infamous Tweet from last fall where Trump claimed he was going to have us all home by Christmas. It seems that was mainly a desperate attempt to score votes right before the election, but caused a significant panic in Afghanistan as that kind of an abrupt withdrawal would have been 10x more catastrophic than what you are watching now. I can promise you the Resolute Support leadership was constantly pushing back on pressure from the Trump admin to expedite the withdrawal, almost to the point of blatant insubordination, and ultimately ended up settling on a compromise of 2,500 troops left in country by the inauguration. We watched the ANA and ANP hemorrhage checkpoints and stretches of highway throughout 2020, and still kept drawing down. The Biden admin actually delayed the Trump timeline from May 1st to September 11th, so making this a left vs right issue is disingenuous. The biggest difference I could see now is what apparently looks like a lack of OGA presence throughout the country, though I was never privy to DoS plans under either administration. Regardless, service members I worked with at every level and nationality all agreed that the Taliban was going to take over within weeks of us leaving.
2. The primary blame for all of this rests solely on the ANA and Afghan people. Claiming we "abandoned" them after spending 20 years trying to better their country is an absolute joke. And saying they didn't have time "to even cover their flanks" is over dramatic nonsense. Trump announced in late fall 2019 that he was seeking to negotiate a peace deal with the Taliban. Then In February 2020 it was announced that we would be withdrawing everyone IAW the peace deal by May 1st 2021. With Biden's extension, GIRoA had 18 months notice this was coming. We also terminated OEF in 2015 and shifted to ORS/OFS afterwards, so the ANA has been having to operate in a lead combat role for over 5 years now. Last year when we were determining which bases to shut down and in what order, ANDSF claimed they were ready and wanted a big airbase. So we decided to give them Kandahar. And when the deadline came for enclaving the US forces into a small compound on the airfield and handing the rest of the base over, guess what? They weren't ready. So that timeline got delayed by another few months.
3. The ANA's incompetence has to be their own responsibility at some point. We did practically everything we could for them. They constantly pestered CSTC-A for more and more money when the problem was almost always their own laziness and inefficiency. I listened to a 3 star talk about how an ANA commander kept asking him for more money for uniforms and boots, only for the general to have to physically take the ANA commander to a warehouse where there were dozens upon dozens of pallets of everything he was asking that had been sitting there for YEARS untouched and undistributed by the ANA.
4. You can keep saying "But Pakistan" when it comes to the Taliban, but it is an objective fact that the ANA was overwhelmingly better trained and equipped than the Taliban. The Pakistani Air Force isn't over there conducting air strikes for the Taliban. The Taliban had a combat strength of roughly 70,000. ANDSF had over 300,000 members, not including local and national police. Those people literally just melted away the past few weeks. Now most of them are probably running around in the mob on the tarmac at HKIA. US Army doctrine states that a defending force should be able to defend a fortified position against an attacking force up to 3 times greater. And here is the ANA, with over a 3 times force advantage, surrendering BAF just a few weeks after we handed it over. And we've still been conducting air strikes this entire time in support of them.
5. Is a terrorist attack more likely now? Yes. But endless COIN wars are becoming a greater threat to national security than the terrorist attacks they are supposed to prevent. Iraq and Afghanistan have greatly sidetracked us and let China and Russia close the gap. The current US military is inadequately prepared for a LSCO fight due to being bogged down in these two conflicts for 2 decades. China and Russia have greatly modernized and are no longer the China and Russia of the 90s. We have an exponentially growing national debt where annual spending on debt interest is eclipsing that of annual defense spending, and all the money we have been shoveling into the Afghan dumpster fire could have been better spent on modernization, readiness, and retention. We must adapt and prevent terrorist attacks by more precise means rather than occupying entire countries for decades.
6. The US cannot, and should not, be the world's police/babysitter. Trump was 100% right on that. That's not being an isolationist, that's being a realist. Your implied solution was that we should just stay in Afghanistan indefinitely and never leave. Yes we are still in Korea as you mentioned. We are also still in Germany, the UK, Italy, Japan, Iraq, Kuwait, and many other places that we have occupied and never left. Where does it end? At some point you're just replaying the downfall of the Roman Empire. The force has already been spread way too thin the past decades. I can't even count how many people I've served with that have over 10 deployments or have spent almost half their career deployed. We are already facing retention and recruiting problems where those that do stay in have to pick up the slack. Soldiers are tired of having to babysit another military that would rather sit around and smoke hash than do their jobs.