I doubt Robinhood claims because every crypto is bound to either go up or down at separate intervals. Dogecoin had a very huge heap for it's pumps late last year and early this year, 2021, so I don't think it is a yardstick to say that dogecoin poss a risk to his business. Every coin/token has it seasons most times and for the fact that prices are no longer going as expected, meant that dogecoin poses a risk to his business.