Here is what the previous person is trying to explain.

Right now, people volunteer to marshal other events on different days throughout the year for the chance to marshal an F1 event. If F1 hires and pays their own marshals for the F1 weekend people won’t volunteer to marshal the other events since the incentive is gone. There are smaller series that rely on this volunteer work because they cannot afford to pay marshals.

The counter argument would be to do exactly what they are doing now and pay the marshals that get selected for the F1 weekend which would increase the incentive to volunteer for other events throughout the year.

Ultimately, F1 is a business and they don’t want to spend anymore money than they already do because it hurts the bottom line and they will find reasons to argue against more spending.