Uh, your resource acquisition would be why.

You need to cap metals, not radioactives, first.  You need to cap them with your starting engineer too.  The best strategy at present is probably to build your factory at the metal point, in range of capping it while you do.  The game loads, you move your engineer and click in a second one, not a whole lot of alternative here.  You should be able to fund two factories right off the bat as long as you expand properly fast.

You want to get metal first because you really need to plop down two factories and spam the bejesus out of frigates as fast as possible, to cap more points.

Odds are there's quite a bit of variation in what you can do, so long as you use your engineer to cap the first metal point.

I've seen a couple of 1st-move tactics. One is to use the first engineer to assist you base making a 2nd engineer until just under 20 seconds have elapsed (clock's on the right just under scorse). Then take that engineer to mfr a Factory next to the nearest metal resource point. That way the engineer takes the resource point while building the factory. When that 2nd engineer comes out have it create metal extractors on every metal extraction point at the base and then at the factory.

This is a decent approach unless the first metal resource point is further away. Then you have to leave earlier for it. Metal's going to be tight so you need to form armies and take more resource points very quickly.

Another I've seen is to take the first engineer and have it create metal extractors at the base. About the same time as the 2nd extractor is built, start building the 2nd engineer. Whichever engineer is ready first makes a Factory at the base and starts building Brutes and Artemis (? rocket unit) having the engineer assist. This cranks out the first few units very quickly. The 2nd engineer pauses before building an armory.

I think this latter approach is better for turtling as, by the time you're finished with the above, you have precisely zero resource points taken.

The ideal is probably somewhere in-between. Metal's imperative to the very early game and must be maintained. How soon you take a radioactive resource is based on how soon you want the other unit types it provides or, perhaps more likely, how soon you want to start building Quanta Generators (I think they're generators, anyway).

Watch some Twitch feeds or Youtube videos. You'll see different approaches and sometimes the creators of them will explain why the do what they do or, even that they don't know what's best. LOL