There's no shortage of people who bought an $800 backpack along with $2000 of other gear, who thought they'd be using them regularly, who later find out that they made a significant investment in a hobby they don't care much about.
Unless you're swimming in money buying gear from those people should be your first choice.
Knowing what to buy is also a huge factor. E.g. the market for backpacks is a bit like the market for racing bikes. You can easily end up spending 3-4x what you actually need because you're convinced that you need the latest & greatest. A bit like the weekend warriors who buy $4000 carbon fiber racing bikes to shave of a couple of kilos, which, unless you're competing, is a complete waste of money.