Thank you for your answers.
The current financial system has collapsed so much that it cannot be compared at all to the opportunities offered by bitcoin.
Almost like with cash, you don't really know.
There are companies (very few) that can do the tracking (between some limits) but you probably won't use them.
Some of the exchanges do shallow check and may lock certain inputs or deposits.
But no, you don't know the coins are really clean.
If you really want clean coins there are miners that offer fresh coins, but they cost more. Again, it's not a much used service.
All in all, the chance you know the history of your coins is small, but nobody cares much. Did you ever cared how dirty your cash is?!
In fiat I can't check the previous owners of the money. As far as I know, with bitcoin, one can trace the path of transactions to the time they were mined. I thought that if bitcoins were used for criminal acts and then sold to someone like me, they could get to me in a possible investigation. Everyone says that bitcoins are only used to scam people.
In addition, we must provide personal information in each exchange.
Which brings me to the next question. How can I sell bitcoin without exchange? There is such a big risk that I will not get my money back.
There is so much negative news about bitcoin on the Internet that I'm sure most are a lie, but it's hard to sift through the truth.