Well, first First of all, you need to understand that the Bitcoin ATM concept has not yet become popular, so how did it fail? There are still many countries in which Bitcoin ATMs are not being used. So how come you claim that the Bitcoin ATM concept flopped?

If your question is further elaborated that Does Bitcoin ATMs can fail?. So yes, of course Bitcoin ATMs can fail for various reasons. The first disadvantage is that you are physically in danger, like someone can attack you maliciously by looking at you due to Bitcoin. The second is the higher fee which can actually cause the failure of Bitcoin ATMs. So these are the points which can cause the failure of ATMs.

And that is why in those countries where Bitcoin ATH has been launched, people still love to use the online version of Bitcoin transactions.