One possible scenario is that It could be a naturally occuring virus that escaped from the lab. The closest match, though not an exact match, was found in bats in a cave in Yunnan province , which is around 1000 miles (give or take about 150 miles) away.
The scientist called "batwoman" who worked on coronaviruses at the Wuhan Inst. of Tech was in Yunnan exploring the caves for bat coronaviruses. Peter Daszak, who provided funding to the WIV, and is the subject of criticism by the Wade paper is on video stating they were researching bat coronaviruses in the caves in Yunnan province. He also states the viruses can be modified.