Reacting is waiting for something to become a problem; anticipating is seeing the potential problem before it has a chance to exert any material effect.
Addressing just what’s in front of you is usually easiest in the short term — especially when it feels like you have a lot in front of you. But the price is more headaches down the road.
Anticipating can be more difficult in the short term (this is where it helps to be an infinitely curious person), but it will spare you from having to deal with certain things unnecessarily.
Exclusively reacting means problems incubate downstream — ignorance may be bliss, but that bliss goes away whenever reality kicks in.
Anticipating is prophylactic — it helps you catch things early, and it’s much easier to quash small issues than big issues.
Anticipating is the rational answer, but it will often feel like the least preferable thing to do.
I’ve got enough to do already.
That may be eternally true, but the effort required to anticipate and plan now will nonetheless always prove to be microscopic relative to what will be required of you if you don’t.