Gaming

You can buy agony infusions which are required for higher tier fractals but they're so cheap in gold no one should spend real world money on it and you'll earn it naturally if you're climbing the fractal ladder normally. A lot of guilds even give away the agony infusions if you are struggling to gain them. I recommend trying fractals at T1 even in LFG, you'll usually find other new players to fractals who are willing and expecting new players to it, but it won't hurt to watch a video if you're nervous

Gw2 really does a good job limiting power so you hit max power quickly that you really are just buying convenience.

This is pretty much only possible because most actual power is account bound and as you can hit near power cap so quickly, you're generally skill/knowledge bound instead of power bound

You can buy fractal infusions with gold for sure, but if you progress through fractals at a normal clip you'll also be able to just make them for yourself. It just expedites things or lets you more efficiently gear other characters, but that's severely overstating how easy it is to get infusions on other characters once you have enough to do t4s and CMs. They aren't dropped by dailies per se, but you DO get them while completing dailies. You can also technically buy infusions in the TP that are stat boosts for gold, but that's literally like. 500 dps out of 40k, at most. it's pretty trivial and stat boost infusions are only really useful for people doing benchmarks

There's a lot you can buy with gold, from runes to legendary weapons. But all of it is either cheap enough to get without a credit card (like the runes) or mostly QoL (like legendaries, which aren't more powerful than ascended).