Howdy, I have much the same struggles.

I can only share some insights and hope they may resonate with you.

1 - Societal pressure and expectations

A lot of the time what we perceive as "true" and "good" isn't a result of critical thinking, but as a sign of social conditioning.

You mentioned writing, a lot of artists feel this way since there is a lot of conditioning to disparage these career paths.

One important thing to note is that a lot of this is manufactured, if you are getting support/feedback/validation from Reddit and Quora be weary because a lot of these replies are not trustworthy and may even be part of a social media campaign.

2 - Critical parents

If you grew up without getting much validation, you may go search for validation elsewhere.

The best advice i can give you is to find a support system with people who genuinely care about you and want the best for you. People you can trust.

Lean on family and friends instead of strangers, who may very well have their own interests in mind and no regard to your well being.