AI safety is a bit like nuclear arms safety. You don't get any safer by not having any nuclear weapons; you just put yourself at the mercy of others with nuclear weapons. The reason nuclear war fare so far hasn't happened is mutually assured destruction. That's why lots of countries seek to have them. Non proliferation treaties have slowed that down but there are probably at least ten or so countries with nuclear weapons at this point.
With AI, it's a lot less clear cut. It's basically going to be about dominance and outsmarting the other side. The downsides are basically more hypothetical / ethical / moral. And when it comes to ethics and morals, there definitely is no such thing as royal we. Countries like China and Russia are likely to choose their own path. Plenty of other countries that will want to get ahead here.