They are super-rich, so they know that their children will be well guarded by security and less likely to die than the little people. Plus it took a while for the Native Roman Emperor to be ousted. Not until there were hardly any Romans left and he was surrounded by foreigners did he get ousted and replaced by a non-Roman.
Perhaps you’re right. But, things seem to move faster these days than in Roman times, what with faster global transportation and instantaneous media to whip up the masses.