Keep in mind, trading retail gold for classic gold is NOT against ToS. Vice versa as well.

Imagine playing Classic WoW, before TBC Classic came out. You're leveling up, like how you did in 2005. It sucks, I know, but bear with me. You run a dungeon but then realize, it's a Troll Mage saying that I don't even have to run it, just stand right there. Okay, I stand there. The Troll Mage comes back in about 15 minutes and says, done. You gained some levels, gained some loot too, and paid the Troll Mage what they were asking for. Now as you leave, you wonder, can I do this all the way to 60? And sure enough, you can. You meet more Troll Mages along the way and you finally hit Level 60. You, not being a Mage, wonder if you should make a Troll Mage as well, get that boosted to 60 and then do these runs yourself and make some gold in the process. So that's what you do. Buy some more Tokens, exchange it for Classic Gold with Retail Gold with another player, and you're off. You hit 60 as a Troll Mage, you go get your pots, then you stick your boosting ad in LFG. People show up, you boost them, get paid, and go about your day. You'll eventually have a ton of gold on you so what do you do? You trade your Classic Gold for Retail Gold (which is much much higher), sell that Retail Gold for $15 Activision Blizzard Bucks or redeem some time.

I've made thousands of gold in Classic WoW. It's P2W.