Hi Matilda. Great question. It's probably a bit influenced by Jean-Paul Sartre's existentialism philosophy. Here's a quote from him:

"There is no reality except in action. Man is nothing else than his plan; he exists only to the extent that he fulfills himself; he is therefore nothing else than the ensemble of his acts, nothing else than his life."

Basically, what I get from this is that, while we're still living, our lives are never a complete project. In Sartre's view, we are only a summation of our choices, but we will continue to make choices, and so therefore can't be defined while living.

In the context of shopping, I find myself in a rush to "reach" something, so to speak. For example, I want my living room to look like it's ready for a magazine shoot, but once I "reach" that, I'll just be reaching for another thing. The living room might feel complete, but then it'll still feel like just a small part of a bigger project. So instead, I try to slow it down. Make more conscious choices. Take the rush out of it because there's no "finish line" to begin with. Of course I still need to buy a couch and coffee table, but I don't have to buy it all at once. I can see how one fits in the space, and then get the other. And so on.

Hope that answers your question. In short, saying "I'll never arrive" is just a way of taking the false urgency out of purchase decisions.