Earlier quoted context omitted.
You're talking about boost-phase interceptors, not mid-course interceptors. Starship to replace GMD (as suggested by credit_guy) doesn't make much sense, but Starship does have the technical ability to launch a massive constellation of space-based interceptors for quite cheap. With Starship, it should be possible to put tens of thousands of interceptors into LEO, and to rapidly replenish the constellation. As for the…
The problem with weapons in space are that they put the opposing super-powers in an impossible position. Hence it forces them to make a move asap to prevent being at a total disadvantage. This is mostly because weapons in space can be used with very little warning. There is little defense, and not even any notice that allows you to prepare or setup a second strike. Plenty of people don't think that's bad, but it seem…
- what if deployment of an effective BMD is covert and piecemeal, and is presented as fait accompli? The first to do that wins, and we only have one real contender. You might say that's a very dangerous gamble, but…
- what response do you envision if the cover is blown? Yes, classic game theory suggests launching everything, but let's think about, say, Putin's options. If he launches, he is guaranteed to die very soon and have his country obliterated. If he doesn't, his nuclear deterrent is indeed worth less now, but it's not given he'd ever need it. Both because it might not be needed during his long and happy life, and because the US is not very keen on attacking random dictatorships despite some historical precedents. So the choice for him is between immediate death and potential problems in the future, and hey maybe it's not actually BMD or maybe it's not very effective, right? Covert/deniable deployment helps here, a lot
So between those two possibilities, I think it's not given that an effective BMD would be as dangerous as you suggest.