No worries - it’s a pretty common misconception that tech companies sell data. I’ve worked on ads systems at big tech companies so I’ve seen some parts of how it works. The companies are very protective of their data as it’s essentially their highest-value asset. Employees can’t see any of your data either - it’s very tightly locked down, with strict ACLs and audit logging.

Large advertisers generally don’t get any special access either - the tools/apps that large advertisers use are mostly the same as what small advertisers / individuals can see and use.