I'm not a politician, but it could lead to an escalating arms race that is expensive and benefits nobody. If Reagan finished SDI, other nations like China/Russ

I'm not a politician, but it could lead to an escalating arms race that is expensive and benefits nobody. If Reagan finished SDI, other nations like China/Russia could feel the need to develop a similar program. They would at a minimum start researching ways to work around the insanely expensive SDI program, which would cause it to be obsolete. The cycle continues and everyone loses money and resources that could be spent on other problems.