Thomas Edison got the process started, but it took him much longer than he anticipated to get a working model. In 1878, when Edison got started, he was so sure that this was going to be easy, he collected money from the Vanderbilts and J.P. Morgan to form the Edison Electric Light Co. before he had hardly begun. A year went by, and Edison still didn't have a workable model.
Big money gets impatient quickly.
Edison was embarassed and frustrated. At first blush, it seems like a very simple problem. Take two wires from a power source and run them through a glass bulb. When you balance the amount of power against the thickness of the wire, the bulb should glow and make light. Basically, a lightbulb is always burning up.