Most of outdoor stuff won't last forever if is used often. However it can be repaired, like boats for example.
Outdoor tents from non-natural fabrics like 20 nylon are pretty sejsitive to UV rays. Cotton tents are much better in that hindsight.
I have proper pair of heavy full leather boots that I have been wearing since 2013 pretty often, sometimes daily and they should live for 10 more years at least.
Good sleeping Bags can last dozens of years.
Older non lightweight Backpacks lived for about 5-15 years but there have been great improvements imho. Not just weight but also better ergonomics or at least more models that fit me better.
Lightweight stuff has been pretty dominant and successful, even in the mainstream, so I guess many are buying new gear to safe weight, rather to replace broken gear. However lighter high-end stuff like Cuben is not as forgiving as medium weight Cordura.