Yes, exactly, and most of those people are those who are not aware of what is happening to the bitcoin ecosystem, but there is nothing bad happening to them, they just need to pay taxes.
I know that if you exchange bitcoin and the bank receives it, they have systems that tell them that you're receiving unusual amounts of money and they report it to IRS.
Launder? You are going to go in jail if you are looking to launder money, that is something ilegal in all the countries all around the world.
So how to launder it to cash without banks/irs knowing? Is the only option buying by sending the btc to someones wallet?
Just withdraw your money (sell) your bitcoins by p2p on localbitcoins, or just use a bitcoin fiat ATM.