Hostile management, 99% of the reason I left. Union contract had been up for renegotiation for 2 years. Company fouled up the schedule then blamed the union for an illegal work slowdown, a completely fabricated charge, and sued us. The judge ruled while the union lawyer was still en-route to the courtroom, more proof it was a setup.
3 months later the company realized how horrible a mistake they had made when they lost 40 million dollars (or more) and had to report to the shareholders that they couldn't follow company growth plans because guess what - they didn't have a contract after 2 years. Almost immediately the company agreed to the union proposed payscale but by that time it was far too little too late, the company had already proven itself utterly untrustworthy and hostile.
My new job required an initial pay cut, has nearly identical long-term income potential, and is harder work. But my new company isn't suing me over a pretend "illegal work action" so it's much better.
The money isn't everything.