The main con that most Monero advocates will talk circles around is that there's no way to easily verify the total coin supply like you can with Bitcoin. If somebody finds a bug to exploit it could go undetected for a long time. And the probability of something like that is higher because the code is much more complex than Bitcoin.
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The funny thing is no Bitcoiners take advantage of Bitcoin's transparent simple math to verify the supply. None of them are making sure all inputs = all outputs let alone every 10 minutes.
All they do is run a node and sometimes type in a command to have a number spit back at them. Exactly like any Monero user.
If inputs=outputs
Supply is confirmed.