I would disagree. If one is highly educated in a specific period of history, or literature, or some other field with poor job prospects despite being highly educated, there's still high competition. Also, given that so many people with phD's want to become professors, the competition for those positions is extremely fierce with the "publish or perish" mindset that academia has been in.

I don't think its just a lack of competition that causes people to become more liberal. Academia is highly competitive.