You're right, about a couple things... You don't need it, that's 100% true. You're also absolutely correct when you say you will justify having that one drink and then it will lead to a downhill spiral in very short order.
I used to do this, I would actually reward myself for not drinking.... by drinking. And others on this forum will likely admit to having done this as well.
It took a lot of relapses for me to understand and accept that it would always happen that way.
The one point I would disagree with you on is that 8 days is nothing. You should be proud of that. We don't want to take our sobriety for granted, because we have no guarantee, no matter how many sober days we count up, that any more will follow... but we have to place value on them. 8 days is not nothing. You may be past the worst of your physical withdrawals at this time, and you have established that you ARE able to pass up drinking. You've done it now 8 days in a row, over a week. You CAN do this.
You might want to start thinking about AA or a support system or some kind of plan for staying on this track, because like a lot of people will tell you, it's not always hard to get sober, it can be hard to keep sober.