I just spent 15 years on staff at a biological research university that housed over 50 PI's and 100's of grad student and assistants. In the fields of genetics,ecology,virology,botany,animal research etc etc etc.
I will point to two current PI's - retired that continue to operate labs in Emeritus status. Meaning on their own time and investing their own money
Grad students that work 18 hour days then volunteer on weekends teaching science workshops to underprivileged children.
World renown scientists and researchers
my anecdotal experience taught me passion being more the motivator,
those that saw money and profit their motivation washed out young in their careers