Riots are typically unplanned explosions of rage. Basically flailing and trying to hurt everyone around you.Morons (Trump included) rioting does not a coup make.
And the coup was not that. Trump spend months and even years fostering that rage and rather than just violently expressing their emotions the coup had a concrete goal. To prevent the legitimate government from taking office and installing a false one in its place.
They're not football hooligans super mad their team lost. They were people actively trying to murder the vice president when he wouldn't abolish democracy for them. They weren't mad they lost, they were mad that Trump wasn't crowned president despite losing, and were using violence to try and intimidate it into still happening, or at least severely punish everyone who stopped them.
I bet that if Clinton had send a mob to tear apart Joe Biden for not bypassing Trump and crowning her president people would suddenly go ''that's not a riot! That's a coup!''