I learned my lesson about RNG the hard way when I was playing another mmo. I spent sooo much money (that I didn't necessarily have to spare) on the RNG system and special boxes like the Scarlet Blade cubes.
The problem wasn't the cubes, though. It was my behavior. I'm prone to gambling addiction, and it showed when I was playing that game. A healthy-minded person can buy just a couple boxes, with money they know they can spare, and shrug it off if they don't win something. Me? I wanted the item so badly I would spend my grocery budget trying to get it. Fortunately, I didn't have a family to feed.
So rule one and two are very applicable to me. Not because the cubes are a scam. They are what they are, a game. A red queen vending machine. A slot machine. A lotto.
Though I disagree the cubes are a scam, I do agree with the guide's rules. Waiting for tiered spending events and being wise with my disposable income are good rules to follow.