Many people do things to reach a point where they feel happy and realxed and let everything but in siddhartha goes without eating ,starvation and fasting to be in  the state of nirvana. the advantages
of getting drunk and drugs are they unwind you bad situations and mistakes to once feel great.
the advantages for drugs is you to feel good and forget all your problems .enlightenment comes from within siddhartha learns enlightenment can't be taught but searched for within. " Both siddhartha and Govinda initially seek Nirvana aggressively and directly."
 Thats why Siddhartha doesnt eat and fast all the time to get close to nirvana. When you are using drugs you at state of trying to forget things that so depressing to you but when your praying you are pray to worship your creator and obey and ask help to Allah to make your stresses less.
 The advantages for meditation and prayer is it relieves your stresses and lets you recover your wrong doings. the disadvantages of drugs is your killing your brain cells and making you do things you wouldnt normally do. Doing drugs is making a fool of yours , embrassment because you are not in controll any more the drugs have taken over your body.
 So what siddhartha is doing  he is teaching himself to be in this state where  He has remove himself from the world so thoroughly that he is not motivated by what the world has to offer him.

In siddhartha the ones who smile or have any happiness in the book is those who have reached enlightenment .  Enlightenment cannot be faked or forced in siddhartha. In siddhartha enlightenment is not described in words but not even siddhartha has a smile upon his face until he reaches enlightenment.