Award winning writer.
Speaking as an award-winning writer of speculative fiction, I can say some of the most egotistical people are writers.
I think the changes in personality due to success are only exposing what is underlying in your psyche; when I won the award - which meant nothing - I lost many friends online because they thought the prize would put me above them.
I did change but all winning the award did was make me more nervous about my work.
I am sure what ticked them off the most was that for months they'd been writing about book signings, sales, and contracts, but here I was with no formal training winning an award. I didn't change, the only change was in how they perceived me.
I knew winning the prize would not change me because I am intrinsically an introverted person who avoids the limelight.
There but for the Grace of God go I; I would hate to become an Amazon bestselling writer as I have seen how some peoples' heads are turned by a little good fortune, I wasn't one of them.
Update - I have changed, but not as people would have expected from me, in 2019 I gave up writing as I don't enjoy it anymore.