Crypto Currents

Wait. I'll just check with our resident digital currency experts and get back to you. Sciforums, after all, is nothing if not a site for learning how to buy, sell and trade digital currencies. You've definitely come to the right place with your questions! Stay tuned.

US cryptocurrency expert jailed for helping North Korea evade sanctions

A former US researcher at a cryptocurrency group has been sentenced to more than five years in prison for conspiring to help North Korea evade US sanctions using cryptocurrency.

He was also fined $100,000 (£76,864). The 39-year-old had been facing a maximum sentence of 20 years in prison and a $1m fine.
Why do Coinbase, Binance etc have BTC to sell?
Where do they get the BTC?
Coinbase and Binance are primarily exchanges. That is, they facilitate peer-to-peer trading. When you want to buy, they link you to someone willing to sell at the same price, and they take a small cut of the trade value (from both the buyer and seller).
They do own some BTC themselves (I think Coin own c.5,000 BTC or so) but that's really just a float. If you buy some direct from them (at a higher fee), they will then buy BTC from someone else. So the end result is much the same as a more direct exchange, but more expensive for the buyer/seller as they're both trading directly with Coinbase / Binance rather than between each other.
Hope that answers your question.