I had the same thought process as you…maybe. I was worried interview prep would mold my answers into what they thought was right, and during the interview I would lose my voice and be “remembering” what to say vice inherantly “knowing” what the right answer was. But prep companies aren’t really like that, they don’t tell you “what” to say just guide you on “how” to find the best answer within your own experiences. I did end up paying some hard earned $$ just to invest in my odds. If I failed, I would always wonder why I didn’t take the time. In the end, could I have passed the interview without it…most definitely. Did it make it somewhat less stressful and borderline fun, yup. You have to know yourself. Do you do large public speaking events already where you answer questions, keep the audience entertained, but have specific subject matter that you must verbatim express? Then knock yourself out. On the other hand, if you’re in your 20s without decades of stories on the tip of your tongue, just spend the dough. My 2 cents.