Drugs are a personal choice HOWEVER;
1) the need to take drugs can say things about how they view life/cope with things - some people use drugs to 'escape' or because they cannot cope with reality, others use them because they think having a good time, no matter what the cost, in important.
2) it is an expensive habit, and if he is doing it everyweek, it will be VERY expensive
3) if he is doing them everyweek, he may well be addicted. This is a difficult rut to get out of and many addicts don't want to get out of it.
4) drugs can have long term effects on the personality of the user. This means he may well change while you are with him and probably not for the better. This will be even more difficult to prevent if he is addicted
5) the short term effects may cause serious or unpleasant incidents; bad trips, erratic behaviour, losing control etc
6) drugs can kill. Do you really want to risk getting that, "I'm sorry miss, but your boyfriend has overdosed on ecstasy and subsequently died of dehydration" phonecall?
You also say that he is "perfect in every way".... you CANNOT know that after only a week or so, even if you have been mates with him for a while. People's behaviour at the beginning of a r/ship is often a nicer or more palletable version of who they really are. People, conciously and subconciously, amend the more extreme or odd aspects of they character when they are with someone new and so it is very difficult to work out what someone is really like until you have been with them for a while.
Also, you have not been with him long enough to see everything he has to offer in terms of values, personality, habits etc.