What does Walt mean by 'Inertia'?

Question

Towards the end of 508 Gliding Over All. Walt and Jesse are awkwardly reminiscing about their times cooking in the RV.

At one point, Jesse brings up the point of how much money they had made at that point and wonders why they didn't buy a newer, more reliable vehicle.

Walt replies with one word:

Inertia

Inertia in it's simplest is one of Newton's laws stating:

An object in rest tends to stay at rest, an object in motion tends to stay in motion.

What does Walt mean by implying inertia kept them from buying a new RV?

Answer 1

They were already moving forward (not necessarily literally, even though they were in an RV) with making the drugs in their current lab. Getting a new RV would have meant stopping that progress, taking a good chunk of money and spending it on something new, and starting over with a new lab in the new RV. Starting with a new lab would mean losing time in making the drugs... getting the new lab set up, getting used to the new setup, etc.

The comment about Inertia refers to the fact that it was easier to keep moving forward, than to stop and start over again.

Answer 2

Inertia is the resistance to change. Walt and Jesse enjoyed cooking in the desert because of the money and the rush from doing so. Therefore, inertia; resisting change, kept them from buying a new rv or moving to a better lab.