Meanwhile I've seen and heard of plenty of personal assistants (nobody uses the term secretary any more) share in the upside of the company through substantial annual bonuses. Often these come directly from their boss's personal funds.
A great PA, and a great person in any position, will make everyone's life better, and help the people on the front line perform to their capability.
based on what?
Why do you think engineers get paid more than secretaries, on average? There's your answer.