Most of the bullied and abused Prince that rose to the Throne do so by colluding with other people, often Nobles
They secretly gathered the support of some Nobles before scheming the deaths of the Imperial Family by doing dirty deeds
Most Princes are like that but Ryden is different
He didn't do much scheme and directly went for the kill. After all, not everyone has the same level of power that Ryden has
In terms of killing power, they are far inferior to Ryden and they cannot replicate what Ryden had done
As such, Ryden's act of killing the Imperial Family without colluding with the Nobles first is a big problem
The resistance his ascension would encounter would be much bigger compared to the other Princes in History
Of course, even a big problem that would give people a terrible headache would also looks like a child's problem with a proper solution
The solution that Ryden already have now