When Nikola was in his third year of college he had a gambling addiction. His addiction caused him to gamble away his tuition and fees. Luckily he managed to gamble it back and repaid his parents, but he did end up not graduating from the college.
After Nikola was tricked by Edison he went to work for AC company to compete against Edison. But Edison was shady and sabotaged them by electrocuting pets with AC motors. Nikola was smart and proved the motors are safe by running currents through himself.
Nikola´s biggest failure was the Tesla tower, and today scientists said it would have never worked. This failure was the start of his depression. He also saved most of his money to build it but it was never going to supply energy to everyone.