I'm not usually much of a conspiracy theorist, but this one seems plausible to me.

When SARS was discovered, it was quickly linked to civet cats as the original host. We still haven't linked covid-19 to a host animal, other than some vague suggestions that it's some kind of bat/pangolin hybrid.

The closest genetic matches to covid-19 were discovered in a Yunnan cave, over a 1000 miles from Wuhan. Samples of those viruses were held in the lab. Seems more likely that samples got out, (with or without modification) than someone else coincidentally went to a Yunnan cave and then went to Wuhan and started an epidemic 10 miles away from the lab.

I've seen better analyses, like the unlikely addition of the Furin site in the spike protein. I'm not quite educated enough to understand all this.

You can easily say that the virus only mutates so fast (1-2 base pair mutations per week). If it's 92-96% similar to the closest natural virus, that's 20-40 years worth of mutations.

So we're missing the natural source. Or it's a chimera, a recombination of 2 viruses. That can happen in nature (i.e. in a pangolin that gets infected with 2 coronaviruses at once). But the Wuhan lab also did published work on gain of function research, making chimeric coronaviruses:

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4797993/

So... not a crazy idea at all.

I don't know how you would blame someone if this is all true. Does China pay for the global economic damage? As I understand it, the funding for gain of function research was international, so it might not be just China at fault.