You still need hundreds of tonnes of rocket fuel no matter what, though.

You don’t have to intercept the satellites in orbit, they fall back to earth in a few years on their own. What SpaceX et al need to defend against is attacks while they are still on the ground or seconds after launch. Next round of investment will put the factories on the moon (only then will we see calls from the general public to Blow Up the Moon)

Back of the napkin math says a bare minimum of ~2000kg of solid fuel in three stages to “get to” GEO using a 3-stage rocket, to deliver 1kg of “something.” You’d need a gravity assist highly elliptical orbit which is a touch harder to pull off (but probably not harder than getting 2000kg of ammonium perchlorate). Plus building the actual rocket, guidance computer, etc.

Not trivial but not impossible. If you’ve got a few hundred million people with nothing better to do, I’m sure a few dozen/hundred could pull it off.