> The bat origin also had no evidence

Of course it had evidence (see https://www.livescience.com/new-coronavirus-origin-bats.html and https://www.bbc.com/news/science-environment-55998157) but there were always questions (https://www.pbs.org/newshour/show/who-report-says-covid-orig...)

Congratulations, you have just discovered why almost every claim "there's no evidence about X" is false. Almost every conspiracy theory - and surely almost every side of a scientific debate - has some evidence behind it. Maybe inconclusive evidence, maybe bad evidence, maybe very weak evidence, maybe even evidence later proven to be false or fake - but there's almost always at least something. The reason is simple - the number of possible theories is infinite, but people's attention is finite. So even the dumbest, most gullible person would select the theories to believe in somehow - and those that have zero evidence to lean on would rarely make the cut, because there's just too many of them, so the probability of any of them to land any significant number of supporters is practically zero. Thus, the theories you've heard about likely to have at least some evidence - but there are questions, as you correctly noted. For bad theories, there would be very small and bad evidence and very large and hairy questions. It's not a 100% rule - hence I say "almost" - but it is very often the case.

For more exploration of the "no evidence" question, I suggest you read https://astralcodexten.substack.com/p/the-phrase-no-evidence...