KNIFE RAFFLE for my steam group! Join now if u play CS:GO =)

Actually yes, it's bad. It's idiotic and to another decent term for it it's honestly pretty disgusting.

Your "friend" stands to make profit from the raffle, in total a group of people are gambling for that knife. They are putting in money for a one in forty chance of winning that knife. So, one person happens to get lucky and 39 just gave someone a free key for really nothing. It's quite literally the definition of gambling and to be honest, it probably goes against some of the policies of steam.

That's why you should read the FAQ. Rules state that you must activate games you win on your account. Breaking the rules get you suspended and sometimes, blacklisted.