It depends on the field. In the sciences (especially biosciences), professors typically have to get money from grants to pay for their labs, and sometimes part

It depends on the field. In the sciences (especially biosciences), professors typically have to get money from grants to pay for their labs, and sometimes part of their salary. Being able to get grants depends on their publishing record, and losing grants and having to shutter or at least downsize your lab is a very real possibility. So in these fields, although your position is secure, your lab and your salary are actually quite precarious.