deorbiting needs propulsion, and quite a lot of energy. Also re-entry generates lots of heat, more so than powered flight. And the thing stays hot.
Rocks don’t just “fall” at orbital speeds.
There are a heck of a lot of smart guys who have been working these problems for decades.
Well missile defense has been around for a while; long enough for unfriendly countries to look for ways defeat the missile shield. That the problem with having so many powerful toys. People fear and fear motivates people to look for ways to circumvent so their weapons get to their targets. The unfriendly countries aren’t like the US, where hubris and a need to show off your capabilities. (shock and awe). They don’t show off what they have, usually. Before the war started in the Ukraine, both Russia and China showed they have weapons capable of taking out satellites.