[ZenGum]

The buddy claims he stole the idea.

Probably the idea was bounced around between a whole bunch of people.

Most likely, lots of different people were independently having the same idea at around that time. It often happens.

Know something, though? The bright idea is so tiny a part of eventual success that it is nearly irrelevant. It is the huge slog of steady hard work that makes the idea viable, then succesful, that counts.