Where the hackers sell your personal information and who buys it

The hackers have the motivation to steal your personal data and credentials as it is very easy for them to monetise these types of attacks.

The threat actors have their own supply chains buried within webs of security and obfuscation. The hackers will steal the personal information, using a suite of attacks that includes phishing emails and stories that will make you react. Once they have your information they sell this onto brokers, who in turn promote their wares through illegitimate social media and Dark Web websites. From there the threat actors purchase the information (using cryptocurrencies for anonymity) in bulk or by the specific target(s) they are interested in and then go on to use the information in their cyber-attacks.

Without the supply chain the motivation for many hackers would not be there.

Darknet markets generate millions in revenue selling stolen personal data | Ars Technica

Clive Catton MSc (Cyber Security) – by-line and other articles