Thus and commas - is this correct?

It's ungrammatical. Correct versions are:

• While most of us associate it with the supernatural or magic, and thus reject its existence, it’s been studied by researchers for many years.

• While most of us associate it with the supernatural or magic, thus rejecting its existence, it’s been studied by researchers for many years.

The parenthetical could be offset by brackets or dashes in each case, giving more measured pauses and adding gravitas to the parenthetical statement.