Your response, with all due respect, is exactly what one would say when one does not possess a strategy that makes money consistently. One of the questions that I may ask when someone is interested in learning a lesson is: "Do you believe a roulette strategy can beat the House Edge?" If your answer is no, you will not qualify for a lesson, reason being, you already have defeated mindset.
If one enters an endeavor and believes they cannot succeed, they will not succeed.
Not really. I can have a "negative" mindset but if the system works and I follow it as per the rules, I will still win. In the remainder of your post you went on to describe the experience of a former student who at first failed and then succeeded, but he didn't fail because of a negative mindset, only because he continued to use his "old" methods.
I don't believe any system can beat the house edge, but it's not the BELIEF itself which causes me to lose. There are other causes (such as that the system doesn't increase the accuracy of predictions).