Something i've been pondering of late:
The more clever(won't use the word intelligent because it can be measured in numerous ways) you are the more likely you are to develop addictions. Same applies to laziness, if you are very smart or clever you can also become quite lazy/complacent.
The addiction theory i think applies to a very smart person because they need constant mental stimulation be that through drugs, alcohol, music etc. People who are clever tend to immerse themselves in something and develop a great passion for it as opposed to someone of lesser intellect, the person of lesser intellect will quite happily meander through life not being particularly stimulated or interested anything.
The laziness theory is quite simple i think. People who are very clever can find the most efficient ways of doing things very quickly, once this is established they don't have to work as hard, repeat this a few times and they will become reliant on this trait thus not work as hard. This can breed complacency which can sometimes trigger a downfall, a vicious cycle of you will
I agree with this also boredom