I actually often see the opposite less intelligent people are often carefree and more happy.

Ignorance is bliss.

Quotes are like bible passages. There is one for every occasion and every perspective. Given one quote, you can find an equally poignant and contradictory quote.

Time and tide wait for no man!

Slow and steady wins the race!

This is why I cringe when I see people leading their lives based on quotes.

Quotation is a serviceable substitute for wit. -Oscar Wilde

A witty saying proves nothing -Voltaire

Being intelligent is not exactly the same as being smart, and no matter how intelligent you may be, if you cannot control the activities of the effects that stick to your consciousness after the fact of what has happened to you in the past, you can't preserve your own true self for a long time, especially in this modern age.

This is only true up until a point where they have to deal with something they don't understand.

Intelligence is apparently correlated with depression and anxiety, as the more intelligent one is the more likely they are to question themselves and their world.

Yeah, except if you're too stupid to even notice how hard life really is.