If you pay off your card every month, they aren’t making any money off you. Pair that with the fact that you have a 50K balance on another card and they have an excuse to lower your limit.
Guido and I put everything we buy on our cash rewards cards and pay them off every month too. So we get cash back for our purchases and don’t pay a cent of interest. I’m sure our card companies would love to dump us or lower our limit too.