The word is "REIN", people, not "reign" when you are talking about your spending or other excesses. I realize we're all a bit removed from the good ole days of using horses as a major form of transportation, but the phrase "reining in ____" comes from those horsey days. You rein in your horse when you want it to slow down or stop. Why do we say you "rein in" your horse? Because you pull on the reins. You know, those leather straps that run from the bridle to your hands? The reins.
Reign, on the other hand, goes with royalty, and not because we associate the British royal family as riding to the hunt on their horses using their reins to tell the horses where to go and when to slow down. No, we simply have a tradition of royalty reigning over the land they rule. (we might note that the Latin Regina would translate to Queen today) Queen Elizabeth is the reigning monarch. Prince Charles would like to reign over the British Empire before he's 100 years old, but that may not happen given family longevity. The reign of King George III was marred (from his POV) by the American War for Independence (aka Revolutionary War).
Had someone been able to rein in King George III's tendency to reign over the colonists by taxing them dearly, we might not celebrate July 4 as Independence Day.
Got it? Thank you for trying.