I didn't saw him pull a single gold lightning (well, except on guaranteed SSR) despite that many pulls. I guess DMM has made gacha more "exciting" by making SSRs surprise-evolve from other pulls?

The amount of Jewels we're about to get is going to explode soon, like 3k per every event. Still, 100k probably means he's been saving up for several months. Or he could've just whaled whenever he wanted to spend premium currency, getting extra Jewels while not spending any. Hard to tell.