Really? I don't think nuclear war is more likely these days than it was during the 60s and 70s. If anything I think that possibility has greatly decreased given the interdependence almost every nation has on other nations.
we've come much closer to blowing ourselves up then we ever
have to space colonies
Considering the vast number of ICBMs and nuclear devices prepared by the US and USSR during that time period, compared to the number of colony ships and slowboats that made it into production, I think that's a fair point.