Don't forget:

- the enemy had plenty of material, technical and financial support from adversarial superpowers who were all too happy to see American lives, money and military resources wasted.

That external support is not fully scaled up yet (despite clear reports of Russian intelligence support for Iran), but you can bet it would be in the event of a major ground assault, occupation, and/or counter-insurgency quagmire.

> the enemy had plenty of material, technical and financial support from adversarial superpower

Vietcong weren't exactly fighting with 'plenty of material'. They used weapons from second world war, sometimes first world war, cheap Chinese crap..

Are you comparing that to Americans aircraft, bombs, helicopters ? It was as asymmetrical as it would be against Iran.