Math guys: Chances of OTM 8 times in a row?

[1C5]

For a 20% ROI player?

This has been happening to me this month about 80% of the days that I have played. It is incredible. Just wondering the math behind this happening so much. I really don't think it should be happening that much (therefore, I suck this month/new leak/really, really unlucky).

Thanks.