Bitcoin was wildly popular on darknet markets even when it was worth less than $10. It's still tied to a dollar value, so it can be used for payments without issue.
Way back in the early days before exchanges, you literally bought and sold them on forums using bootleg paypal ripoffs (since paypal didn't recognize virtual money = buyers could refund)
I put off my 20,000 BTC purchase because it was so sketchy.
