Has your biggest disappointment been in someone else or was it in yourself?

No. 
~

That doesn't answer the question Randy. 

Never someone else. I dont rely on my happiness from anyone but myself. That goes for any disappointment i may feel also.

This a tough question for me.  You're making me think when I'd rather not.   You're also putting a crimp in my fun today making me thing about things like this.  It's a toss up depending upon the day and what I'm thinking about.  I've been disappointed in so many people during my life.  Yet, I've been greatly disappointed in myself a few times.   If I were pressed, I'd say I was greatly disappointed in someone else.  My parents specifically.  They didn't want children nor the responsibility that comes with raising them.  I was left to my own devices at a very young age.  If it wasn't for my grandmother, I don't know if I would have survived my childhood.

I feel disappointment in myself. I have different issues that have brought my self confidence down and I have let negative people dictate to me my self worth.

probably both

This probably sounds odd, given what a cheerleader I am for the human race in general. I do believe people are capable of amazing things, but at the end of the day, I mostly expect humanity to fall on its face because that's what it does best. I expect people to screw up, and because of this, I'm almost never disappointed in anyone, especially if I know them well. Me, on the other hand... I expect more out of myself. I know my own shortcomings and pitfalls better than anyone else, and so I'm better-poised to plan for them and overcome them. If I fail at something, it's because I didn't plan for a contingency that was within my control. I can't think of a single thing that ever really mattered that I failed at, but in the ebb and flow of life, the scale would lean toward disappointment in myself if both were weighed. 

People have disappointed me before, but no one has disappointed me as badly as I have. :(

Myself first. 

Myself.... I gave my word to a close friend about self harm and relapsed shortly after. It took another 11 hard years before I could try again. That disappointment turned into something that I am proud of now. It's been 4 years now with minimal thoughts due to a couple people from sodahead.