Getting told you are easily replaceable - red flag or a basic truth in this industry?

Context: asking boss for more money, more responsibility, more opportunity along with others at a 12-attorney and 100-employee PI firm, only to get told "you're all replaceable so I don't care" (I'm paraphrasing, that was the gist of it.

How true is this? Are lawyers easily replaceable? Only half on our staff seem to be able to function without hand-holding or excessive management involvement, so I have to wonder if this is a stretch to claim that any attorney is replaceable so easily.

Maybe it varies by practice area as well. I am a litigator and am the only attorney in the firm in the past 5 years to even have a trial (let alone 4 trials) while other litigators seem scared to go to court, so I'm a little shocked at the stance being taken by a boss that we could so easily be thrown out the door and replace tomorrow if we don't like it.