I think the disconnect is that it is extremely unlikely that any of us have made what a MLB player or manager makes. For us, a vast majority of us would take a 30% raise if a competitor offered it to us. Not all, but most. For most of us, that's probably not going to be a lot more than $30K per year, if that. For most of us, that $30K/year makes a big difference though. Significantly more than $30K/year, and it can be life-changing.
But what if we already had made $30M in our career? Would an incremental couple of million make a big difference in our lives? Probably not, because we've already made $30M. Barring idiotic financial mismanagement, we (should be) set for life for several generations.
Counsell made at least $20M in 15 years as a player and at least $10M as a manager with MKE for 9 years, maybe closer to $40M total. Does he really need an extra $3M/year? No, he's already made at least $30M. Will an extra $3M be life-changing for him? No, he's already made $30M.
I think that's the point. If he hadn't played 15 years in the majors and had worked his way up through the minors as a manager and never had a big payday before, sure, I could understand this first big contract being life-changing.
I think that most of us though, if we had already made $30M in our career, wouldn't jump to a competitor for a raise if our employer really wanted us to be there and offered us $5M/year to stay. We would have to really not like it there or want to stick it to our former employer for some reason to jump ship when we're already set for generations.
Leaving for more money, when you've already made at least $30M in your career and have an offer of $5M/year to stick around, is either greed or revenge.