This depends to a great extent on what we call “personal data.” For the most part, only those with a need to have our personal data should have access to them. That would be a rather limited group of people.
I would assume that our “personal data” include such things as Social Security numbers, health data, and financial data. There are very few people who really need access to these things. In particular, I cannot think of anyone other than ourselves who need access to all of the personal data.
There will be some people who need access to parts of our data. For example, our doctors and our insurance companies clearly need to have our health data so they can treat us and pay for our treatment. When we apply for a loan, the institution from which we are seeking the loan will need to have our financial data so they can know whether we are a good risk for a loan. The government needs to have our Social Security numbers and our tax data. However, there is no one else who needs to have access to all of these things in cyberspace. That is because no one has any legitimate use for all of our information.