Does having tack work?

i upgraded and tacked all my showing horses.  is it really worth it or did i just waste my money?

Tack is worth it if you plan to show your horses, but it can only help increase their chances in shows it's not the magic path to winning automatically. Fully upgraded tack adds bonus stats that help your horse compete, but to have actually winning horses you also have to pay attention to their specialty stats, and non-specialty stats to an extent, training level( higher levels increase luck factor), and where they are in the stat bracket. Horses at the higher end of the stat bracket (i.e. 140-149 in the Novice one bracket) tend to do better than those in the lower end (100-120 for Novice 1). In the end there's always a bit of random chance thrown in so even the best horse doesn't' win every show, they just have a better chance of winning. If you do not have tack your horse is missing out on the stat bonus granted by tack and would have less of a chance of winning against a fully tacked horse with the same stats and training level.