Ricky Williams chooses pot over football.

[AChimp]

People don't get addicted to the pot itself; they get addicted to the high. This is the same reason why people get addicted to a bowl of ice cream like you said: it makes them feel better.

Feeling better = good, therefore stuff that causes you to feel better is also good. It's a perfect example of classical conditioning.

Some people have a higher conditioning threshold and don't get addicted as easily. The reason why it escalates into harder drug use is because the high from pot isn't enough anymore, or there's the temptation to experience an even higher high (feeling even better > good).