If you and I were walking down the street and saw a dead cat on the side of the road, I would tell you that cat was possibly hit by a car, and I'd be justified in saying that. I have only two pieces of circumstantial evidence: the location of the dead cat in the place where cars drive by, and the fact that cats are sometimes known to have been run over by cars.

The WIV is in the exact place where the outbreak began, and houses the same strain of viruses, and researches them by breeding new variants. And, viruses have escaped from laboratories before. It occurs fairly regularly.

This is far from a "conspiracy theory", not to mention that it doesn't even involve a conspiracy.

Cats get hit by cars every day. Lab escapes of contagious diseases are extremely rare[1]. That doesn't figure into your analysis?

Imagine instead that you pointed to the squashed cat and demanded that I debate the Very Important Possibility that the cat was in fact killed by an illegal Chinese helicopter.

"Uh, dude..." I reply. "That cat was clearly run over by a car."

"But no!", you say. "There have been helicopter slayings in the past, right? And there are no track marks! And the Chinese are known to be developing helicopters that could totally do this to a poor cat. There is an airport just miles away! Look at all these other people who believe in the helicopter theory! YOU ARE SUPPRESSING THIS IMPORTANT EVIDENCE!"

Get the point?

[1] In fact recognized newly evolved strains of existing viruses outnumber "lab leaks" by a factor of something like tens of thousands. Pick any one disease and it's basically guaranteed that it's not a lab leak.