why do Asians eat weird things like bats, venomous snakes, wolf puppies, Koala, etc..?

Yeah. Why don’t they eat normal things like, aspartame, potassium benzoate and Blue #4? 

We eat bee vomit, 
Chicken eggs,
Cow's milk,
Bull testicles,
and some other pretty strange stuff when you think about it.  

Strange, unrealistic ideas.

You may want to keep in mind your own ancestors ate bugs, lizards, or what ever they could find.

To this day Native Americans serve 'Puppy soup' to honored visitors. The value of dog puppy a special honor.  

Ever eat pork? Or entertain what 'industrial pork' exposes that animal to? ( like a pig cares about it's environment?)

.. Well if you are old enough to remember free ranging pork and have exposure to farm animals... 'industrial pork' explains the sour taste of todays pork.

I don't think they eat Koalas; anyway they taste strongly of eucalyptus.

ask a baby calf why doncha

The most obvious answer would be that they have different animals available to choose from. Everyone eats weird things. If you eat eggs you eat bird embryos.

It is mostly done as a way to flaunt one's wealth. These exotic game animals are expensive and only the rich can afford to do it. So, if someone goes to a restaurant and orders some of these expensive animals then other people around them will know that they are rich.

Another reason is that people believe that rare animals may have some rarely found health benefits. They do not eat these animals because they taste good. In fact, there is another belief among some Chinese that things that taste bitter are good for the body.

That said, people in other parts of the world also have strange eating habits. Americans for example may eat crayfish, bull testicles, rattlesnake meat, and they may buy kangaroo meat imported from Australia. In contrast, kangaroo meat used to be dyed green when exported to Hong Kong to prevent unscrupulous merchants from using it to make Chinese sausages, which are red colored and made of pork. It shows that not all Chinese people will eat exotic animals. In Europe, Germans and the Swiss, as well as Brits, may eat dogs, until recently when such practice was outlawed.

There are also credible reports that Brits ate human flesh which were once sold illegally and in the black market. The French has no qualms eating snails and horse meat, something most Brits would not touch. Archaeologists who excavated early European settlements in America found that they ate human flesh to stave off starvation in Jamestown. Of course there is also scientific evidence that some of the people who explored the Arctic ate human flesh when they got stranded and were facing starvation and certain death.

Other people around the world would eat insects, and big caterpillars. Africans and some SE Asians will eat monkeys and apes as "bush meat" so it is nothing weird about the Chinese eating wild game.

The government can't feed the people; so they opened it up to private enterprises. These enterprises are largely unsupervised leading to diseased animals being sold on the wet market.

They ARE HUNGRY! And there are a LOT OF THEM!!

Don't think Koalas would have been there. They're only found in Australia.
And an Asian person may ask you why do you eat such strange animals as cows.

Because a lot of mainland Chinese are uneducated with the dangers of eating such animals. And because there are 
many sources on Chinese social media stating that consuming such animals would make you more healthy.