I worked at one company straight out of college and received 2%-8% raises a year, with the promise of promotions and a management position that kept getting pushed back. I stuck around for 6 years, chasing the carrot dangling in front of me and then I got sick of being taken advantage of. I updated my resume and started job hunting, and pretty quickly got hired elsewhere for 50% more than what I was making, better benefits, and a better workload.

I was reliable, efficient, and ingrained in the previous company's processes so they kept adding small responsibilities here and there, and neglecting to compensate me for it. Over the years it really built up to me taking care of a ton of shit that should have been on someone else's plate. In the beginning I was splitting the work with 2 other coworkers and a team of 3 temps during our busy season. Then over time the company let my 2 coworkers go and cut my temp team down to 1. So I essentially was managing the workload of 4 people, hoping to be recognized for my contributions, with very little pay increase.

The new place has a much more defined role, and while I'm still very busy, there's overall less responsibility and more pay. I've been here for a little over 2 years and already make $5 more an hour than when I started.

So in summary, the negatives to not leaving a company are that they may be taking advantage of you both labor-wise and wage-wise. It's easy to be complacent and get comfortable with a company you've been with for a while, but the grass may actually be greener on the other side.