Tarot cards are not "magic" and do not show the future. People who use tarot cards and who make any money from the practice are the ones who become proficient at the skill called "cold reading", where they use observation of their mark to learn clues about them to assist in the "reading". They draw these conclusions from verbal, paraverbal, and non-verbal communication - body language, facial expressions, clothing worn, colors chosen, apparent level of wealth, apparent sociopolitical background, apparent sexuality, relationship status, etc. etc. ad infinitum. It isn't "magic", it's simply training oneself to utilize good observational skills paired with critical thinking and logical deduction. Of course, most of these conclusions are guesses that may or may not be accurate, and much leeway is taken up by the illogical mental trick that the mark will use to make the "prediction" fit his life situation via a process called rationalization.
Your "future" is a combination of almost infinite possibilities that stem not only from your actions and choices but also from the actions and choices of everyone around you and even those who simply come within physical distance or even within sight of you. Every thing you do is like throwing a rock in a pond - some are small rocks, some are larger rocks, and everyone you contact is also throwing their own rocks in - and where those circles meet they overlap and even create new waves as they spread out to meet even more waves. There is simply no possible way to begin to even guess the outcomes of all choices.
The idea that a bunch of store purchased, mass marketed, hokey cardstock cards could in any possible way tell you what the future will hold is nothing short of pure insanity. If they could show you the future, then they would deal out the exact same cards each time until you got up and did something, which thereby changes the future - any choice has repercussions into the future that cannot be predicted.