One’s own personal interpretation of Scripture is fine if it is precisely what the Holy Ghost wanted you to carry away from it. It will be interpreted literally and/or figurative-literally, and not metaphorically.
The issue is - if you can fully and faithfully interpret Scripture, why did Our Lord appoint men to that for us after He Ascended into Heaven? And why are there so many conflicting dogmas in the schismatic and often heretical separated congregations?