system
Given the following post, respond as if you're commenting on Reddit:
human
[Batman] Who have characters theorized Batman to be other than Bruce Wayne?
gpt
Most commonly, people assume Batman isn't a single individual, but a team of well-paid mercenaries. After all, no one person can be THAT GOOD at all the exploits Batman is known for. Someone hiring a shadowy private army is much easier to believe than one man dressing like a bat and patrolling the city every night of the year. This theory often gets strengthened as the Bat Family grows, and people are shown definitive proof that there are multiple people working under the Bat-label. 

Especially early in Batman's career, a lot of people didn't think Batman was a living person at all. But some kind of shadowy, magical figure. Maybe a demon, or other form of otherworldly avenger. A lot of GCPD's earliest hunts for Batman were conflated with chasing Bigfoot and other cryptids, because he seemed very much like one. 

There is actually a rather loud group of people online who SWEAR that Bruce Wayne is Batman. But they're usually seen as conspiracy nutjobs and people looking for attention by shouting the most insane ideas possible. Bruce actually encourages this, and even posts some of these ranting posts himself, in order to sow further confusion and distrust of the idea.