I honestly think it's easy if you try hard enough, at least at the beginning. Just make a bunch of good and entertaining quizzes and it goes by pretty quick.
From my experience, maybe around 750k is when it gets more difficult to advance. The jumps get bigger, and right now, it takes like 20-30k just to go up one rank. So, yeah. It really depends on what you think is hard.
I've been at #191 for probably months now. It's a lot easier for people around my rank to advance when they've got like 500+ quizzes, but I've only got about 100 and I haven't advanced past #191 since February.
Probably ~500 is the threshold. I usually gain a rank every day or two, but that's just carried by two quizzes. It'll usually take about 1,000 takes to pass someone and I only get about 500-700 per day
From my experience, maybe around 750k is when it gets more difficult to advance. The jumps get bigger, and right now, it takes like 20-30k just to go up one rank. So, yeah. It really depends on what you think is hard.