[Rerarom]

You can live just off your usual salary, you don't need grants if you're frugal.

[tmoot]

Typically the university pays professors salary and gives you a startup fund.

Professors have to bring in grant money to fund students, build a lab, travel to conferences to advertise the work, etc.

Plus the university gets a little slice of the grant.

[UncleMeat]

If you don't bring in grants you'll be fired. And good luck funding a lab w/o grants.

[Rerarom]

Not everywhere is like the US.