This is definitely real.

Bustabit charts are a great illustration of this, as people roughly win and lose together, which amplifies the typical variance most sites see.

This is an week old chart from bustabit I generated at day-intervals: https://i.gyazo.com/cb23db21c23de9ca44e600eda85fbec1.png and almost every down-spike in profit, is accompanied shortly by an up-tick. This is normally the same player that won, losing it back. And the effect is even more pronounced on a smaller times interval. Wagered always goes through the roof too, when people are lucky. It forms part of my theory that most players are loss-constrained (as a rough rule of thumb, will play until the house edge whittles down their playing budget).

And you can also see when players lose, the wagered drops. Like the recent leveling off in wagered, with the big uptick in profit.

(Also, incidentally the first giant downspike in profit, has no accompanying up-tick was actually because I lowered the site limits (in response to the whale winning) which drove him to lose their money else where. Lesson learnt. =))