Its expensive to build rockets. Most rocket startups require at least 100 million $ to get a rocket into orbit. But a rocket into orbit is a far cry from an anti sat weapon. That technology is gone run you another 10-20 million $.

And then that kills 1 sat. SpaceX has many 1000s of sats.

So a small rocket like Electron cost around 8+ million $, lets say 6 million $ in cost. Plus lets say 1 million for the anti sat.

So you need to invest a couple 100 million $ into the development and produce many rockets. So you can calculate 7 million times * 6000, that gone be around 42 billion $.

Of course you would need to launch them from somewhere without a government that can stop you. Taking out vital infrastructure used by the US military tends to make people a bit angry. And neither China, Russia or Europe will want you anywhere close to them. This is likely gone make this much more expensive. Maybe you can make a deal with the Taliban? But they likely don't want that heat either.

So this is just a pure fantasy scenario.

> Maybe starting a cascading effect?

That's not gone happen. Far to low in orbit. As soon as they don't have propulsion they will drop lower. Until then the others can slightly raise their orbit.

There is not even a single nation state who has the capability to take out Starlink.

And no amount of people who burn down 5G towers could ever pull this off.