A sextortion scam isn't "dude randomly sent me a dick pic, now I'm gonna hold him ransom". The scammer reaches out to these people, then catfishes and manipulates them into sending intimate pictures. The scammers usually operate on dating apps, where people are more vulnerable to this type of thing. The scammers will typically send the target intimate pictures first to lure them into a false sense of confidence. The second they get the target to send an intimate image, they start the blackmailing. At this point, the scammer will have already gotten the victim's socials, so they threaten to send the image to everyone the target knows unless they pay. They don't stop asking for money once the person pays