What is "old" clothing anymore?

I watch a lot of videos from various content creators on YouTube. Some fashion specific, some more lifestyle based and many who are focused a lot on sustainability. I've noticed that a lot of them have been referring to clothes as "really old" when in fact they mean no more than 3 or 4, sometimes even one 1 year(s) old. That surprises me.  

Is this concept of "old" clothing being under 5 years old unique to them because they all work in world where by nature anything older than a year is outdated or is that something that most people think these days? I understand that you constantly have to be evolving on social media and looking at what is on topic now in order to stay afloat, but even some of the more sustainably minded content creators refer to their not-so-old-to-me clothes as old, so maybe it's more of a widespread thing? Maybe it's only "old" relative to other content creators' clothing? 

I'm currently wearing my sister's old tank top that is at the very least 14 years old. My underwear is probably at least 10 years old. My shorts are around 5-6 years old. Am I just disgusting? It all still cleans up just fine! Perhaps my family just raised my sister and I in a bit of a stranger way than I realized...  

I worry a lot about shopping at less than sustainable companies because unfortunately we don't have any storefronts here that stock sustainable brands and sometimes you just need to see things in person (or...did before a pandemic I guess). Is shopping at fast fashion houses still "fast" if you end up wearing the pieces for decades at a time? Aside from the obvious ethical problems of these institutions, when does the sustainability of the product in the consumer's wardrobe outweigh the overall sustainability of the corporation? And if we don't believe we can participate in a system without taking on the whole of the ethical responsibility, are we ever really able to consider ourselves as individuals more sustainable while still living in the capitalist society that we do?  

A lot of thoughts for a Sunday morning. Time for some coffee.

.... *queue existential dread stemming from coffee consumption*.